C or X=-3 I need more characters
It's 15624 meters because 28*18*31

To solve the given system of equations for substitution you:
1. Solve in one of the equations a variable.
For the given options the one that is correct is solve the first equation for y, by adding x to both sides:
Answer:
A. 3rd equation
B. 1st equation
C. 4th equation
D. 2nd equation
The final value within the square root can't be negative or else the solution is imaginary, and you also cannot divide by a value of zero.