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.

Question

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MrRoyal MrRoyal · Answer 1 · 2021-02-07T02:15:32+01:00

Answer:

[tex]B = 4x + 8[/tex]

A box = $11

Step-by-step explanation:

Given

[tex]Total = 7x + 13[/tex]

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

So, we have:

[tex]A = 3x + 5[/tex]

Solving (a): Find B.

To find B, we make use of:

[tex]A + B = Total[/tex]

Make B the subject

[tex]B = Total - A[/tex]

Substitute values for Total and A

[tex]B = 7x + 13 - (3x + 5)[/tex]

Open bracket

[tex]B = 7x + 13 - 3x - 5[/tex]

Collect Like Terms

[tex]B = 7x - 3x + 13 - 5[/tex]

[tex]B = 4x + 8[/tex]

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

This means that:

[tex]Total = 90[/tex]

Substitute 7x + 13 for Total

[tex]7x + 13 = 90[/tex]

Collect Like Terms

[tex]7x = 90 - 13[/tex]

[tex]7x = 77[/tex]

Make x the subject

[tex]x = \frac{77}{7}[/tex]

[tex]x = 11[/tex]