Solve using substitution.

–9x + 6y = 18
x = 4

To solve this system of equations using substitution, we can first solve the second equation for x, and then substitute this value into the first equation.

Given: x = 4

Substituting this value into the first equation:

-9(4) + 6y = 18

Simplifying:

-36 + 6y = 18

Next, we can add 36 to both sides of the equation to isolate the variable:

6y = 54

Finally, we can divide both sides of the equation by 6 to solve for y:

y = 9

Therefore, the solution to the system of equations is x = 4 and y = 9.