math
posted by Anonymous .
Stan wants to arrange his books in order of size. Half of the books are medium, 2/10 are large and 12 are small. What is the total number of books Stan has?

7/10 of the books are not small.
3/10x = 12
x = 12 / (3/10)
x = 12 * (10/3)
x = 120/3
x = 40 
let, total number of books= X
Small= 12
Remaining books = X12
now,the remaining books comprise:
1/2X= Medium
2/10X= Large
Therefore,
1/2X+2/10X=X12
Solve for X and you will get the answer!!