Zachary is helping his younger brother, Sterling, learn his multiplication tables. For every question that Sterling answers correctly, Zachary gives him 3 pieces of candy. For every question that Sterling answers incorrectly, Zachary takes away two pieces of candy. After 7 questions, if Sterling had answered 2 more questions correctly, he would have earned 31 pieces of candy. How many of the 7 questions did Zachary answer correctly?  Choose the correct choice from the following choices:
A) 6
B) 7
C) 8
D) 9
E) 10

Rationale: "i got two equations : 3 x - 2 y = 25 x + y = 7 3 x - 2 ( 7 - x ) = 25 3 x - 14 + 2 x = 25 5 x = 39 x = 7.8 or between 7 and 8 . ( ans b )"
Answer: B