Answer:
x = -5
y = 2
Step-by-step explanation:
3x + 4y = -7 -------eqn 1
-3x - 8y = -1 ------eqn 2
First, let's take eqn 1, to find the value of y
3x + 4y = -7
Make y the subject of the formula
4y = -7 - 3x
Divide both sides by 4, to get y
4y/4 = -7 - 3x / 4
y = (-7 - 3x) / 4
Substitute y into eqn 2
-3x - 8y = -1
-3x - 8(-7 - 3x) / 4 = -1
Open the bracket with -8
-3x + (56 + 24x )/ 4 = -1
LCM = 4
(-12x + 56 + 24x) / 4 = -1
(-12x + 24x + 56) / 4 = -1
(12x + 56)/4 = -1
Cross multiply
12x + 56 = -4
12x = -4 -56
12x = - 60
Divide both sides by 12 , the get the exact value of x.
12x/12 = -60/12
x = - 5
Insert the value of x = -5 into the equation 1
3x + 4y = -7
3(-5) + 4y = -7
-15 + 4y = -7
4y = -7 + 15
4y = 8
Divide both sides by 4
4y/ 4 = 8/4
y = 2
Hint, to confirm if the values are correct
Pick any of the two eqns
Let's pick eqn 2.
-3x - 8y = -7
x = -5
y = 2
-3(-5) - 8(2) =
= 15 - 16
= -1
So therefore, our values are correct
