Problem on Solving Equation by Substitution Method

Topic : Substitution Method

Problem : Solve 6x + 7y = 8 and -4x + y= 40 by Substitution Method

Solution :
6x + 7y = 8 --------- (1)
-4x + y= 40 --------- (2)

lets take the second equation
-4x + y= 40
add +4x on both sides
y = 40 + 4x
Now substituting this value of y in the first equation, we get
6x + 7(40 + 4x) = 8
6x + 280 + 28x = 8
32x = 8 - 280
32x = - 272
divide both sides by 32
x = -272/32
x = -8.5
Now substituting value of x in equation (1)
-4x + y = 40
-4(-8.5) + y =40
+34.0+y = 40
y = 40 - 34
y = 6
So x = -8.5 and y = 6