Can you give me a challenge 5th grade math question

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

Acomputer store bought a program at a cost of $10 and sold it for $13. find the percent markup

Aye asap pls ! markin da brainiest too ! btw da step choices are all add, distribute, divide, n subtract