2(x - 5) = 110
2x - 10 = 110
Add 10 to both sides.
2x = 120
Divide by 2 on both sides.
x = 60
A15=243
74-61=13
87-61=13
So they're adding 13 every time.
A15 is 11 terms from A4 which is the last one you are given so 11*13=143
143+100=243
Add 2x and x to get 3x
Answer:3x
