Question

12 is 1/3 of what number

Answer 1

12*1/3

 Multiply across which is 12*3=36

Answer: 36

Answer 2

"is" means equals
"of" means multiply
let "what number" be represented by "x"

so we get the equation: 
12 = 1/3 * x  [solve for x]
x = 12 * 3    [multiplied 3 to both sides]
x = 36    [<- answer]