41/2 + 1 + 2 + 1 1/4 + 1/2 + 2/4 how did you get the answer

Your answer is 9 3/4.

You should first add all of the whole numbers. 

Four plus one plus two plus eleven equals eighteen.

Then add all of  the fractions with common denominators. 

one halve plus one halve plus one halve is one and one halve.

one fourth plus one fourth is one halve.

one and a halve plus a halve is two. two plus eighteen is twenty.

4+1+2+11 = 18 
1/2+1/2+1/2 = 11 1/2 
1/4+1/4 = 1/2 
1 1/2+ 1/2 = 2 
18+2 = 20

The answer is twenty