Answer:
9a + 4b
Explanation:
Start by multiplying the two values inside the parentheses (5a + 2b) by 2 to get 10a + 4b - a. Then, subtract the single a from the end to get 9a + 4b.
The variables a and b cannot be combined, so both variables must still be present in the final answer. Order of operations is also very important, because if you subtracted the a before multiplying, then you would get 8a, which isn't correct.