Estimate the sum of 9 12/15 + 1 2/6 a 11 b 13 c 10 d 12 answer fast

A 11 because 9+1 is 10 and there are the remainders

 
A.) 11

Explanation: 
To estimate the sum of these numbers, simply add the whole numbers of 9 and 1: 
9 + 1 = 10 
and then judge what the fractions will add up to roughly. 12/15 is almost 1, and it is more than 1/2, so it will round up to 11. 

But to be sure you can check: 
9 12/15 + 1 2/6 
9 24/30 + 1 10/30 = 10 34/30 = 11 4/30 = 11 2/15