The two equations given in the question are y = - 3x And y = 6x - 9 Let us now substitute the value of y from the first equation to the second equation, we get y = 6x - 9 - 3x = 6x - 9 -3x - 6x = - 9 - 9x = - 9 Multiplying both sides of the equation by -1 we get 9x = 9 x = 9/9 = 1 Now let us put the value of x in the first equation, we get y = - 3x = - (3 * 1) = - 3