How do I find the dimensions of a rectangle given area?

Question

20x-48

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|------------------| 7

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(That's supposed to be a rectangle)

The given area is 504 sq units

Answer 1

(20x - 48)(7) = 504

140x - 336 = 504

140x = 840

x = 6

20(6) - 48 = 72

72 * 7 = 504

Answer 2

Let: Length, L = 20x - 48

Width, W = 7

Area, A = 504

A = L*W

504 = (20x - 48)(7)

504 = 4(5x - 12)(7)

126 = (5x - 12)(7)

18 = 5x - 12

5x = 18 + 12

5x = 30

x = 6

L = 20x - 48

L = 20(6) - 48

L = 120 - 48

L = 72

Check:

A = L*W

504 = 72 * 7

504 = 504 Yes!

Therefore, the length and width of the rectangle are 72 units and 7 units, respectively.