Help me out again lovely geniuses.

To solve the system of equations below, grace isolated the variable y in the first equation and then substituted into the second equation. what was the resulting equation? 3y=12x x^2/4+y^2/9=1

The bolo cavern outside of vandalia is 421 ft below sea level. a little more than75 miles away. mt owens is 7295 feet above sea level. what is the difference in elevation between the bolo cavern and mt owens?

Use the linear combination method to solve the system of equations. explain each step of your solution. if steps are not explained, you will not receive credit for that step. 2 + 9 = −26 −3 − 7 = 13