Given the system: 3x + 6y = 18 2x + y = 12 which variable, in which equation, would you solve for first to use the substitution method? question 1 options: solve the 1st equation for x. solve the 1st equation for y. solve the 2nd equation for x. solve the 2nd equation for y. using the substitution method, what would be the first step to solve the given system? x = 2 - y 3x + 4y = 20 question 2 options: solve the 1st equation for x. substitute 2 - y in for x in the 2nd equation. graph the two equations substitute 2 in for y. given the work as shown for solving the system, what will be the value of y in the solution? question 3 options: y = 0 y = 5 y = 25 y = 35