The tip would be $17.26
All you have to do is multiply 86.29 x .2 (20%)
The answer will be reflect (2, - 3 ) in x = -1
Notice this is a geometric progression since each number multiplied by some factor equals the next number in the sequence, in this case,

Then by applying the formula for sum to infinity of a geometric progression,
I had that question yesterday
3x^(2)+4x-3x-5-2=0
3x^(2)+x-7=0
Discriminat= b^(2)-4ac= 1^(2)-4(3)(-7)= 1-12(-7)=1+84=85
The discrimination is bigger than 0 (delta>0) therefore there are 2 real solutions