7.4 hw answers

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7.4 HW Answers

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7.4 HW Answers. (4, -1). (19, 16). 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. (5, 3). (5, 6). (-½, -2). (-7, -12). (9, -3). (2, 1). (-10, -5). (4, 4). 10x + 2y = 155. 12x + 3y = 189. $14.50 balls. $5 bags. (-2, -2). x = -19 + 9. x = -10. 5(y + 9) – 3y = 7. y = -19. (-10, -19). - PowerPoint PPT Presentation

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7.4 HW Answers

1.

2.

3.

4.

5.

(4, -1)

(5, 3)

(-½, -2)

(9, -3)

(-10, -5)

6.

7.

8.

9.

10.

(19, 16)

(5, 6)

(-7, -12)

(2, 1)

(4, 4)

10x + 2y = 15512x + 3y = 189

$14.50 balls $5 bags

2 23

y x

(-2, -2)

5(y + 9) – 3y = 7y = -19

x = -19 + 9x = -10

(-10, -19)

5 6 7x 7 5 6 7x

1 135 5

x

-1/5 0 13/5

-11 0 5

3 8x 3 8 or 3 8x x

5 or 11x x

Scoring Your Homework• Count how many problems you missed

or didn’t do

• 0-1 missed = 10• 2-3 missed = 9• 4-5 missed = 8• 6-7 missed = 7• 8-9 missed = 6

• 10-11 missed = 5• 12-13 missed = 4• 14-15 missed = 3• 16-17 missed = 2• 18-19 missed = 1• 20-21 missed = 0

Table of Contents

Topic Page #...7.1 Solve Systems By Graphing 767.2 Solve Systems By Substitution 777.3 Solve Systems By Combination 787.4 Multiplication w/ Combination 797.5 System Word Problems 80

1. You are selling tickets to a play. The price of a student ticket is $5, and the price of an adult ticket is $8. You sell 556 tickets and you collect $3,797. How many adult and student tickets did you sell?

Step 1: Choose your variables

S = student ticketa = adult ticket

1. You are selling tickets to a play. The price of a student ticket is $5, and the price of an adult ticket is $8. You sell 556 tickets and you collect $3,797. How many adult and student tickets did you sell?

Step 2: Write two equations:A) One that represents the value of the items

5s + 8a = 3797B) One that represent the quantity of items

s + a = 556

Step 3: Solve the system using substitution or elimination

5s + 8a = 3797s + a = 556(–8)

5s + 8a = 3797

-8s – 8a = -4448+

s = 217 -3s = -651217 + a = 556

a = 339

2. A bag contains dimes and nickels. There are 18 coins in the bag. The value of the coins is $1.25. How many of each type of coin is in the bag?

Step 1: Choose your variables

d = # dimesn = # nickels

2. A bag contains dimes and nickels. There are 18 coins in the bag. The value of the coins is $1.25. How many of each type of coin is in the bag?

Step 2: Write two equations:A) One that represents the value of the items

0.10d + 0.05n = 1.25B) One that represent the quantity of items

d + n = 18

Step 3: Solve the system using substitution or elimination

0.10d + 0.05n = 1.25

d + n = 18(–5)10d + 5n = 125

-5d – 5n = -90+

d = 7 5d = 357 + n = 18

n = 11

(100)

3. Kylie has 4.50 in dimes and quarters. She has 3 more dimes than quarters. How many quarters does she have?

d = # dimesq = # quarters0.10d + 0.25q = 4.50

d = q + 3

0.10(q + 3) + 0.25q = 4.500.10q + 0.30 + 0.25q = 4.50

0.35q + 0.30 = 4.50

0.35q = 4.20q = 12

= 12 + 3 = 15

4. An adult ticket to a school play costs $5 and a student ticket costs $3. A total of $460 was collected from the sale of 120 tickets. How many student tickets were purchased?

a = adult tickets = student ticket5a + 3s = 460

a + s = 120

5a + 3s = 460a + s = 120(–3)

5a + 3s = 460

-3a – 3s = -360+

a = 502a = 100

50 + s = 120s = 70

5. A drummer goes to Guitar Center and buys drum sticks and brushes. The wood sticks that he buys are $10.50 a pair, and the brushes are $24 a pair. He buys twice as many pairs of wood sticks as brushes, and ends up spending a total of $90. How many pair of sticks and brushes did he buy?

d = drum sticksb = brushes10.50d + 24b = 90

d = 2b

10.50d + 24b = 90d = 2b

10.50(2b) + 24b = 9021b + 24b = 90

45b = 90b = 2

= 2(2) = 4

6. The sophomore class is selling pretzels and popcorn at a school event to raise money for a dance. They charge $2.50 for a bag of popcorn and $2 for a pretzel. They collect $336 during the event. They sell twice as many bags of popcorn as pretzels. How many pretzels do they sell?

z = pretzelsp = popcorn

2.50p + 2z = 336p = 2z

2.50p + 2z = 336p = 2z

2.50(2z) + 2z = 3365z + 2z = 336

7z = 336z = 48

= 2(48) = 96

7. You went to Home Depot and bought two types of plants. One type was a flowering plant while the other was non-flowering. The flowering plant cost $3.20 each and the non-flowering plant cost $1.50 each. You purchased a total of 24 plants for $49.60. How many of each type of plant did he buy?

f = flower plantn = non-flower

3.20f + 1.5n = 49.60f + n = 24

3.20f + 1.5n = 49.60f + n = 24(–15)

32f + 15n = 496

-15f – 15n = -360+

f = 8 17f = 1368 + n = 24

n = 16

(10)