Can someone please help me on this?

Solve 2x+y=3 x+y=5 in substitution method

Find the quotient with the restriction.

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]