1 + 4 = 5
2 + 5 = 7 but you have to add the 5 from the previous addition problem, and it'll give you 12
3 + 6 = 9 but you have to add the 12 from the previous addition problem, and it'll give you 21
If you continue the pattern (4+7, 5+8, 6+9, 7+10) then 8 + 11 will be 96.