SOLUTION: I really forgot how do do this type of problem $15 is what percent of $75? 4% of what number is 21? What number is 12.5% of 56? Could you please help me? Thank you -Rozz

Algebra ->  Percentages: Solvers, Trainers, Word Problems and pie charts -> SOLUTION: I really forgot how do do this type of problem $15 is what percent of $75? 4% of what number is 21? What number is 12.5% of 56? Could you please help me? Thank you -Rozz      Log On


   

Question 29775: I really forgot how do do this type of problem
$15 is what percent of $75?
4% of what number is 21?
What number is 12.5% of 56?
Could you please help me? Thank you -Rozz
Answer by Cintchr(481) About Me  (Show Source):
You can put this solution on YOUR website!
Percentages can be done many ways. First you need to know some vocabulary.
"of" means multiply
"%" means part of 100
"is" means equals
"what number" is usually represented by x or n
There is a siple formula that will work for all three types of problems you have stated here.
+%28is%2Fof%29+=+%28percent%2F100%29+
$15 is what % of $75
+%2815%2F75%29+=+%28x%2F100%29+
cross multiply
+%2815+%2A+100%29+=+%2875x%29+
divide both sides by 75
+%28%2815%29%28100%29%29%2F%2875%29+=+x+
now just multiply the numerator out and divide by the denomonator.
or reduce the fraction first, and then multiply and divide. as I did here.
+%2815%29%284%29%2F%283%29+=+x+
+60%2F3+=+x+
+20+=+x+
and you are done.