x = number of shaded squares
3x = number of unshaded squares
This is because there are 3 times as many unshaded squares compared to shaded
unshaded = 3*(shaded)
Since there are 5*8 = 40 squares overall, this means,
shaded+unshaded = 40
x+3x = 40
4x = 40
x = 40/4
x = 10
There are 10 shaded squares and 3x = 3*10 = 30 unshaded squares.
So you'll shade in 10 squares in any fashion you prefer.
