The easiest way to solve this is by substitution. This means that you set one of the equations equal to a variable and you plug that variable into the variable of the other equation. The second equation (y = 7x) is already set up this way so we will plug it into the first equation.
-5x + 2(7x) = 9
-5x + 14x = 9
9x = 9
(9x)/9 = (9)/9
x = 1
You have found x. Now, plug this number into the second equation (y = 7x) to find the value of y.
