Let r be the number of right answers, w the number of wrong answers
8r - 3w = 110
8r - 80 = 3w + 30, 8(r-10) = 3(w+10)
x-10 must be a multiple of 3, and y+10 must be a multiple of 8. Use "k" as a positive constant.
x-10 = 3k, y+10 = 8k
r = 10+3k
w = -10+8k
Add these two and get
x+y = 11k
Because there are 25 questions,
x+y <= 25, so k must be 1 or 2. However, if y is to be positive (which it must), k >1. K must equal 2
Plug into x+y=11k, and x+y = 22.
Jess answered 22 questions.