Respuesta :
It appears that each consecutive answer is added to the next operation such that ((1+4)=5)+2+5=12, because 2+5=7, but when added to (1+4), the answer is 12, and so on.
Thus,
(1+4)=5 + (2+5)=12 + (3+6)=21 + (8+11)=40
Thus,
(1+4)=5 + (2+5)=12 + (3+6)=21 + (8+11)=40
