Answer:
x = -3/4
Step-by-step explanation:
Simplify the equation.
5x - 3(3x + 7) = y
5x - 3*3x + 7 *(-3) = y {Distributive rule}
5x - 9x - 21 = y
Combine like terms
-4x - 21 = y
Now, substitute the value of y = -18
-4x - 21 = -18
Add 21 to both sides
-4x = -18 + 21
-4x = 3
Divide both sides by -4
x = -3/4