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?
10x + 18
4x + 8
21x + 65
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.

A box = $11

Step-by-step explanation:

Given

Represent the first order with A and the second with B.

So, we have:

Solving (a): Find B.

To find B, we make use of:

Make B the subject

Substitute values for Total and A

Open bracket

Collect Like Terms

Solving (b): Cost of a box of light bulb

This means that:

Substitute 7x + 13 for Total

Collect Like Terms

Make x the subject

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