Answer: 59/120 (choice D)
Add up the values in the "math" column and the "11th" row to find the total number of people who are either in 11th grade, in math, or in both.
So,
(12+10+8+7) + (14+5+3) = 59
represents the number of people who are in either category. This is out of 120 (given). This is where 59/120 comes from.