Before we get started, it is good to remember PEMDAS - the acronym that tells you the order to carry out equations.
P = parentheses
E = exponents
M = multiplication
D = division
A = addition
S = subtraction
Knowing this, we should start by doing the equations
within each parentheses.

So we did the addition and subtraction pieces within each group leaving us with the above equation. Now let's multiply:

20 is the answer.