Answer: x = 9
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The diagram shows:
Recall that the area of a parallelogram is equal to the base times height
area = base*height
We're told that the area is 117 square units, so that means 13x = 117.
Divide both sides by 13 to isolate x
13x = 117
13x/13 = 117/13
x = 9
The height of the parallelogram is 9
Note how:
area = base*height = 13*x = 13*9 = 117
which helps confirm we have the correct height value for x.