The perimeter of a rectangle with sides x+6 and x-6 is equal to 48 inches. What is the value of x?

(Since the perimeter is the length of each sides added up. Two sides are equal to x+6 and two are equal to x-6)

2 (x+6) + 2 (x-6) = 48

(break out the brackets)

2x + 12 + 2x - 12 = 48

(12 and - 12 cancel out and "disappear".)

2x + 2x = 48

4x = 48

(Rearrange for x)

x = 48 / 4

x = 12 inches

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