The area of a rectangle is 17 1/2 in² and it’s shorter side is 3 1/2. What is the length of the longer side?

Formula for the area of a rectangle:

A = lw         (A = area        l = length(longest side)       w = width(shortest side))

You know:

w = 3 1/2 or 3.5

A = 17 1/2 or 17.5          So substitute/plug it into the equation

A = lw     Plug in 3.5 into "w" since w = 3.5, and 17.5 into "A" since A = 17.5

17.5 = l(3.5)     To find l, isolate/get the variable "l" by itself in the equation. Divide 3.5 on both sides to get "l" by itself

5 = l        The length is 5 in

PROOF

A = lw      Plug in 3.5 into "w" and 5 into "l"

A = 5(3.5)

A = 17.5 in²