why the percent change from 80 to 50 different from the change from 50 to 80?

Question

i've found that from 50 to 80 it is a 6% increase, and from 80 to 50 its a 3.75% decrease, but i dont know why...

Answer 1

Because the denominator of the change is different.

It's basic math. In a fraction X/Y, X is the numerator, and Y is the denominator. If X stays constant and Y changes, the result changes.

In a change from 50 to 80, the denominator is 50.

In a change from 80 to 50, the denominator is 80.

In both cases, the numerator is 30.

You're a decimal off, btw. The changes are 60% and 37.5%.

Answer 2

The difference is 30 in both cases, but in the first case you're starting with only 50 and in the second you're starting with 80. The 30 is a bigger percentage of 50 than 80.