What is the value of Y and Z respectively? 3/4=Y/6=15/Z​

How do i put 3(x+7) in distributive property

Tom drove 206 miles in 3.9 hours. estimate his average speed.

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]