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)
Answer: The dimensions of the painting are 12 x 15 inches.
