And i have to be done with my work by tomorrow

let length of painting = L
 and width = W
from area = length times width
180 inch^2 = L  times W
but L = 5/4  times W
180 inch^2 = 5/4 times W times W

W^2 = (4 x 180)/5
W = 12
but L = 5/4 x W
L = 5/4 x 12
L = 15

The dimensions of the painting are 12 x 15 inches.