Question

Substitution method
6x-7y=5,3x+y=-1​

Answer 1

`x = - (2)/(27)`

`y = - (4)/(5)`

Explanation:

Lets call

`6x - 7y = 5`

equation 1

`3x + y = - 1`

equation 2

using equation 2, we would make y the subject of the formula as it would be easier

`y = - 1 - 3x`

This would now be called our equation 3

Now the next step is to substitute equation 3 in equation 1

`6x - (7( - 1 - 3x)) = 5`

`6x - ( - 7 - 21x) = 5`

`6x + 7 + 21x = 5`

`27x = 5 - 7`

`27x = - 2`

Divide both sides by 27
`(27x)/(27) = - (2)/(27)`

`x = ( - 2)/(27)`

Substitute the value of x in equation 2

`3( ( - 2)/(27) ) + y = - 1`

`- ( 2)/(9) + y = - 1`

`y = - 1 + (2)/(9)`

`y = - ( 8)/(10)`

`y = - (4)/(5)`