See photo for drawing.
Words:
Suppose a square is 100%,
50%: the square is divided into two equal parts, and one of them is shaded, therefore it is 50%.
25%: the square is divided into 4 equal parts, and one of them is shaded, therefore it is 25%.
150%: there are two squares, each divided into 2 equal parts, and 3 of them is shadowed, therefore it is 150%.