Question

Explain why a change from 20 to 40 is a 100% increase, but a change from 40 to 20 is a 50% decrease.

Answer 1

Because 20 has to be doubled to become 40. While 40 is twice as much as 20 so you just divide 40 by 20 to get 50%.

Step-by-step explanation:

20 x 20 = 40 = 100%

40 / 20 = 50%