Question

220 is 20% of what number? Explain

Answer 1

0.20a=220

Where 0.20 is the decimal form of 20% 
a is the unknown number

0.20a=220
-------   -----
0.20     0.20
a=1100

220 is 20% of 1100.

Answer 2

220= 20% "of" y -"of" means multiply! Convert the percent to a decimal
220= .2 * y -divide 220 by .2
1100= y