This problem is about combined operations. We have a square power, a subtraction and whole products.
To solve this we can use PEMDAS which is an strategy to remember the order of operations, that is, Parentheses, Exponents, Multiplication-Division, Addition-Subtraction, that's the right order to solve.-
According to PEMDAS, we solve the power first:
Then, we solve multiplications:
Finally, we subtract:
Therefore, the given expression is equal to 240.
Just remember, PEMDAS dictates the right order to use operations.