Question

How do you solve the linear system using substitution `x = 16 - 4y` and `3x + 4y = 8`?

Answer 1

`x = color(blue)(16 - 4y` ......equation `(1)`

`3x + 4y = 8`.........equation `(2)`

substituting equation `(1)` in equation `(2)`
`3color(blue)((16-4y)) + 4y = 8`

`48 - 12y + 4y = 8`
`48 - 8y= 8`
`- 8y= 8-48 = -40`
`y=-40/-8`
`color(blue)(y=5`

substituting `color(blue)(y` in equation `(1)` to find `x`
`x =16 - 4y`
`x =16 - 4.5 = 16-20`
`color(blue)(x = -4`

the solution for the system of equations is
`color(blue)(x= -4 and y = 5`