Help with maths problem

Can anybody help finding the missing value in this number pattern?

I won't provide the full solution but I'll help get you started.

You can make the number 94 in the following way:

(2*12 + 21 + 2)*2 = 94

You can make the number 144 in the following way:

(2*9 + 14 + 4)*4 = 144

Perhaps you can use this to work out the solution.

That method would give 39, but that is not one of the answers available!?