Which two numbers, from amongst the given options, should be interchanged to make the given equation correct

Which two numbers, from amongst the given options, should be interchanged to make the given equation correct?

A.            6 and 8

B.            7 and 2

C.            2 and 8

D.            20 and 8

Sol:

Here we need to try options in the giving equation

Use option 1

=72-20-12=40

Option A is the correct answer.