What is the sum of one sixth, two twelfth, and one third.

First, make a common denominator, like this:
1/6=2/12
2/12=2/12
1/3=4/12
3/4=9/12
1/2=6/12

Then you just summarize them like this:
2/12+2/12+4/12+9/12+6/12=2+2+4+9+6/12=23/12

The answer is: 23/12

There you go!