Given:
80% correctly; if 16 correct, what is the total?
16/y = 80/100
cross muliply
16 x 100 = 80 x y
1600 = 80y
Divide 80 on either sides.
1600 / 80 = 80y / 80
80 and 80 cancels out.
20 = y
16/20 x 100 = 80%
