Question

18 is 60% of what number

Answer 1

Let n be the number 18=60% of n
18=0.6n
18/0.6=n
30=n

Answer 2

18/n = 60%/100% 
18/n = 3/5 
Cross Multiply Then Divide... 

18*5/3 = n 
to get n = 30 

You could find out 1% = 18 ÷ 60 = 0.3 
100% = 100 x 1% = 100 x 0.3 = 30 

the answer is 30