What percent of the circle below is shaded?
a. 30%
b. 37.5%
c. 60%
d. 62.5%
the picture shows 3 shaded parts out of 8.

If the 8 parts are all exactly the same size,
then the shaded portion is  3/8  of the circle.

To change any fraction to a decimal, do the division:

           (3)  divided by  (8)  =  0.375 .

To change any decimal to a percentage,
move the decimal point two places that ==> way.

              0.375  =  37.5 %
 

First, you take 3/8, which gives you 0.375.
Since this is in percent, you multiply the previous answer by 100% (100% is equal to 100/100, which is equal to 1, and thus does not affect your number).
0.375*100%=37.5%, which is answer B.
Hope this would help~