The cost of 4 cookies, 6 doughnuts, and 3 boxes of doughnut holes is $8.15. The cost of 2 cookies, 3 doughnuts, and 4 boxes of doughnuts holes is $7.20. What is the cost of a box of doughnut holes?

$1.25

Step-by-step explanation:

This can best be determined using a set of linear equations that are solved simultaneously.

This pair of linear equations may be solved simultaneously by using the elimination method. This will involve ensuring that the coefficient of one of the unknown variables is the same in both equations.

Let the cost of a cookie be c, cost of a doughnut be d and that of a box of doughnut hole be h then if cost of 4 cookies, 6 doughnuts, and 3 boxes of doughnut holes is $8.15, we have

4a + 6d + 3h = 8.15

and the cost of 2 cookies, 3 doughnuts, and 4 boxes of doughnuts holes is $7.20 then

2a + 3d + 4h = 7.20

Dividing the first by 2

2a + 3d + 1.5h = 4.075

subtracting from the second equation

2.5h = 3.125

h = 1.25

The cost of a box of doughnut holes is $1.25

D. 5x + 3 = 17

Weight of each book = x pounds = 2.8 pounds

Step-by-step explanation:

Jada’s teacher fills a travel bag with 5 copies of a textbook. The weight of the bag and books is 17 pounds. The empty travel bag weighs 3 pounds. How much does each book weigh?

A. 3(x + 5) = 17

B. 3x + 5 = 17

C. 5(x + 3) = 17

D. 5x + 3 = 17

Weight of the empty travel bag = 3 pounds

Copies of book = 5

Weight of each book = x pounds

Total weight of 5 books = 5 * x

= 5x pounds

Total weight of the bag and books = 17 pounds

The equation is:

Total weight of the bag and books = Weight of the empty travel bag + Total weight of 5 books

17 = 3 + 5x

Can also be written as

5x + 3 = 17

Solve for x

5x + 3 = 17

5x = 17 - 3

5x = 14

x = 14/5

x = 2.8 pounds

Weight of each book = x pounds = 2.8 pounds