SOLUTION: 18 is 20% of what number? I don't understand this way of finding "x". This chapter has an example of 25/100 = x/40 ------->100x = 1000x-------> x = 10 Help!!

Algebra ->  Percentages: Solvers, Trainers, Word Problems and pie charts -> SOLUTION: 18 is 20% of what number? I don't understand this way of finding "x". This chapter has an example of 25/100 = x/40 ------->100x = 1000x-------> x = 10 Help!!      Log On


   

Question 56991This question is from textbook
: 18 is 20% of what number?
I don't understand this way of finding "x". This chapter has an example of
25/100 = x/40 ------->100x = 1000x-------> x = 10
Help!! This question is from textbook

Answer by Scriptor(36) About Me  (Show Source):
You can put this solution on YOUR website!
Hello,

If 18 is 20% of a certain x, then that means that: 20*x /100 = 18
You only take 20% of x, that's why you multiply x by 20/100 (it makes x smaller)
So: 20*x/100 = 18
Multiply both sides by 100 to obtain: 20*x = 1800
Divide by 20 at both sides:
x = 1800/20 = 90
This means that 20 % of 90 = 18