Marisol is painting on a piece of canvas that has and area of 180 square inches. the length of the painting is 1 1/4 times the width. what are the dimensions of the painting?

Formula for the rectangle area is a * b, In this case we know that:

a * b = 180
a (width) = unknown
b (length) = 1 1/4a

We can write it down as:

a * 1 1/4 * a = 180
a² * 1 1/4 = 180                   / ÷ 1 1/4 (both sides)
a² = 144                             / square root (both sides)
a = 12

Doublecheck:

a = 12
b = 1 1/4 * 12 = 15
a * b = 12 * 15 = 180 (so it's correct)

The dimensions of the painting are 12 x 15 inches.