Let's ignore the whole numbers and just focus on the fractions currently.
We have 3/4, so we need to convert that into 12ths
Multiply the fraction by 3
3(3/4) = 9/12
Now our fractions are:
7/12 + 9/12 + 5/12
16/12 + 5/12
21/12
Subtract 12 from 21.
21 - 12 = 9
We have 1 and 9/12 as our sum.
Sum up our whole numbers now.
1 + 4 + 2 + 7
5 + 2 + 7
7 + 7
14
We have 14 as our whole number and 9/12 as our fraction.
Your simplified sum is 14 9/12 (or 14 3/4 if simplifying the fraction).
Your answer is D.) 14 3/4.
I hope this helps!