As usual, it is best to form a pattern for this kind of problem.
For this, the pattern is (a*b)+a
That is, 1+5 = 1*5 + 1 = 6 2+6 = 2*6 + 2 = 14 3+7 = 3*7 + 3 = 24
Finally, 5+11 = 5*11 + 5 = 55+5=60
While 60 is the PREFERRED answer, 40 is a viable answer too.
But the advantage of using patterns is, you can find the answer to any two random variables
without having to consider the chronological arrangement.