Question

How do you solve `4x+3y=-22` and `-8x+y=58` using substitution?

Answer 1

`x = 193/22 and y = 1410/11`

Explanation:

`4x + 3y = -22 - - - eqn1`

`-8x + y = 58 - - - eqn2`

By Substitution Method..

From `eqn2`

`-8x + y = 58 - - - eqn2`

Making `y` the subject formula..

`-8x + y = 58`

Add both sides by `8x`

`-8x + y + 8x= 58 + 8x`

`y = 58 + 8x - - - eqn3`

Substituting `eqn3` into `eqn1`

`4x + 3y = -22 - - - eqn1`

`4x + 3(58 + 8x) = -22`

`4x + 174 + 24x = -22`

`4x + 24x + 171 = -22`

`28x + 171 = -22`

`28x = -22 - 171`

`28x = 193`

`x = 193/22`

Substituting the value of `x` into `eqn3`

`y = 58 + 8x - - - eqn3`

`y = 58 + 8(193/22)`

`y = 58 + 1544/22`

`y = (1276 + 1544)/22`

`y = 2820/22`

`y = 1410/11`

Therefore;

`x = 193/22 and y = 1410/11`