Hi is it posible to give me som anser for matematic

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

Percent increase and decrease. original number: 45 new number: 18

The average length of a king cobra is 3.7 m. the record length is 1.88 m longer than the average. how long is the record holder?