Answer:
Step-by-step explanation:
To solve this problem, first you have to use the order of operations stands for parenthesis, exponents, multiply, divide, add, and subtract from left to right. Remember to use the order of operations stands for "Please Excuse My Dear Aunt Sally."
Do parenthesis first.
Next, exponent.
Multiply & divide numbers from left to right.
Finally, add & subtract numbers from left to right.
As a result, the correct answer is 21.