Question

Solve the following using substitution method

Answer 1

2a + 2b = 7 ...1)

4a + 3b = 12 ...2)

In equation, 1)

a = (7 - 2b)/2 ...3)

Putting value of a in equation 2) we get :

4 × (7 - 2b)/2 + 3b = 12

2( 7 - 2b ) + 3b = 12

14 - 4b + 3b = 12

b = 2

Putting value of b in 3) we get :

a = ( 7 - 2×2)/2

a = 3/2 = 1.5

Now,

2x - 3y = 16 ...5)

x + 2y = -6 ...6)

x = -6 - 2y

Putting above value of x in eq 5) , we get :

2( -6 - 2y ) - 3y = 16

-12 - 4y - 3y = 16

7y = -28

y = -4

x = -6 - ( 2× -4 )

x = 2

Hence, this is the required solution.