For the order of operation use PEMDAS
Parenthesis
Exponent
Multiplication
Division
Addition
Subtraction
For memorizing the order you could say
Please
Excuse
My
Dear
Aunt
Sally
For this question, we use the Pythagorean theorem.

We know the lengths of the legs, a and b.


Now, let's solve for the hypotenuse, c.


Take the positive square root.

Hope this helps! :)
Site vandal. Do not answer.
Answer:
21
Step-by-step explanation: