-3x + 7y = -16 --------------------------------------(1)
-9x + 5y = 16 -----------------------------------------(2)
We will first eliminate y
To do that, we will make the coefficient of y in both equation(1) and (2) to be the same
We can achieve this by multiplying through equation(1) by 5 and then multiplying through equation(2) by 7
That is;
-15x + 35y = -80 --------------------------------(3)
-63x + 35y = 112 ---------------------------------(4)
subtract equation (4) from equation(3)
48 x = -192
divide both-side of the equation by 48
x = -4
Similarly, we will eliminate x
To do that, we will make the coefficient of x in both equation(1) and (2) to be the same
we can achieve this by multiplying through equation(1) by 9 and multiply through equation (2) by 3
That is;
-27x + 63y = -144 ------------------------------(5)
-27x + 15y= 48 -----------------------------------(6)
subtract equation(6) from equation (5)
48y = -192
divide both-side of the equation by 48
y = -4