The answer is C. The sum of 36 and 9, multiplied by 5.
I believe the “x” here is extra, and you might be trying to use it as a multiplication sign instead. Because “x” would be “a number” in these type of problems. So let’s rewrite this:
5(36+9)
First, whoever we see parentheses, we do them first. The answer to addition is sum. So the answer to 36+9 would be the sum of 36 and 9. After you find the sum, which is 45, you would multiply it by the number outside the parentheses, which is 5. So the answer is the sum of 36 and 9, multiplied by 5.
Hope this helped!