Samuel bought a jacket for $16 in January. The cost of the jacket increased to $24 in September. What percent of the original price is the new price?

Write a proportion first, change over original, like this:

8 x

16 100

(I got 8 because the difference between 24 and 16 is 8 and I got 100 because percents are out of 100.)

Cross multiply 8 by 100 and you get 800.

Divide 800 by 16 and you get 50.

It changed by 50%