Help with this math question

Answer: option J: 128 joules

Explanation:

1) From the table you try to find which relation best fits the data.

2) Your best first assumption is that the data may fit a proportional relation.

3) To prove that you find the ratio of Energy ouput to Amount of chemicals.

Doing that you find:
 20        32         48       60
----- =  ------- =  ------ = ------ =  4
  5          8           12      15


4) Then you have found a direct relation whose ratio is 4 joules / mol. So, you can apply that constant to the number of moles given:

Energy = 4  joules / mol × 32 mol = 128 joules