I am going to assume that you meant 40(15 x 40)2,, but if not then please let me know and I will fix my answer for you.
The first step for solving this is to multiply the numbers in the parenthesis.
40 x 600 x 2
Now multiply the first two numbers together.
24000 x 2
Multiply the final two numbers together to get your answer.
48000
Let me know if you have any further questions.
:)