math help plz,show me how you did it and the answer?

Question

in 2004 in the US,21.5%of 8th graders have used illicit drugs.There are about 400 8th graders @ TRMS(thunder ridge middle school).If these statistics are true,about how many 8th graders have used illicit drugs??

Answer 1

well the easy way to do this is...21.5 kids per 100 so you just multiply 21.5 times 4.....but the equation to do this is as folllows....
is/of X %/100 then cross multiply

Answer 2

G 21.5% is the total amount of users
400 is the total population
R how much of the population are users?
E 21.5 = x
____ ____
100 400
so how do you get from 100 to 400? multiply by 4
S 100 times 4 = 400
therefore 21.5 times 4 =86
S 86 of the 400 students have used drugs

Answer 3

The problem asks you how many 8th graders are
21.5% of 400.

Two ways to work this problem:
21.5% x 400
0.215 x 400 = 86 8th graders

or
21.5 /100 x 400