Which of the following expressions are equivalent to x + y - z

How to use order of operation in 20 divide by 4 multiply 5 = 1

Need so much on this one how many yards?

Use mathematical induction to prove the statement is true for all positive integers n, or show why it is false. 1^2 + 4^2 + 7^2 + + (3n - 2)^2 = [n(6n^2-3n-1)/2]