Answer :

24 = 100%
21 =  x%

Cross Multiply

24 * x = 100 * 21
24x = 2100
x = 2100
        24
x = 87.5

Solution: 87.5%
so 21/24=x%
percent means parts out of 100 so
21/24
divide the fraction out
0.875
this is out of 1 so
0.875/1 times 10/10=8.75/10 timmes 10/10=87.5/100
the answer is 87.5%