math
posted by lucy .
What is the formula for finding these??
1. 30 % of 90
2. 70 is 10 % of what?
3. 4/10 of 30
4. change 2/8 to a percent
Please help me with these formulas! Thanks!

The word "of" means multiply.
Change the percent to a decimal.
30% * 90 = 0.3 * 90 = 27
0.1 x = 70
x = 70/0.1 = 700
I'll be glad to check your answers for the other problems. 
so.. 3. 4/10 of 30=
4/10 x 30/1=12
and 4. 2/8 to % would be 8 into 2 which equals .25= 25 % 
Both are right! :)