How do I find the answer to this when using 3.14 for pi

Rai compares two cable plans from different companies. which equation gives the correct value of mm, the number of months for which plans a and b cost the same?

Which recursive formula can be used to determine the total amount of money earned in any year based on the amount earned in the previous year? f(n+1)=f(n)+5

To solve the system of equations below, pedro isolated the variable y in the first equation and then substituted it into the second equation. what was the resulting equation? { 5y=10x {x^2+y^2=36