In my point of view the easiest approach to solving this problem would be by determining the distance between the given points (the midpoint and the other given point) --- (1) and then going through all the answer choices and matching their distance to the midpoint --- (2). This may seem like a hard approach, but you can eliminate many of the answer choices.
The answer is the last choice, so let's prove it.
As the distance between points (1,5) and (9,3) respectively (1,5) and (- 7,7) is the same, we proved that our answer is the last choice.
0.15 cents is 10 percent of 1.50, and that multiplied by 2 is 0.30 cents. 0.30 cents is equal to 20 percent, and the difference between 1.50 and 1.20 is 30 cents.