Question

A store owner spends 7x + 13 dollars on two orders of boxes of light bulbs, including shipping.

Part A
If she spends 3x + 5 dollars on the first order of light bulbs, which of the following represents how much she spends on the second order?
A. 10x + 18
B. 4x + 8
C. 21x + 65
D. 10x + 8
Part B
If the store owner spent a total of $90 on both orders, how much does a box of light bulbs cost in dollars? Enter the number in the box.

Answer 1

B

11 dollars

Explanation:

7x+13 is the sum of the two order

you know that one order is 3x+5, so if you subtract it from the total you get the other order

7x+13-(3x+5) =7x+13-3x-5 = 4x+8

if he spent 90 dollars in total then we can say that

7x+13 = 90

7x=77

x=11

11 dollars per box