The perimeter of a rectangular notecard is 16 inches. The notecard is 5 inches wide. How tall is it?

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The perimeter of a rectangular notecard is 16 inches. The notecard is 5 inches wide. How tall is it?

Perimeter of a rectangle P is:
P = 2l + 2w

We have:
2l + 2w = 16

We are given w = 5, so we have:
2l + 2(5) = 16
2l + 10 = 16

Plugging this into our equation calculator, we get l = 3.