Question

when solving the following system of equations by substitution what would be a correct first step x=y–7 3x+15y=-1

Answer 1

The first step is to replace the value of x from the first equation with x in the second equation:

x=y-7

3x+15y=-1

3(y-7)+15y=-1

3y-21+15y=-1

18y=-1+21

18y=20

y=
`(20)/(18)` =
`(10)/(9)`

x=
`(10)/(9)`
`- 7`

x=
`- (53)/(9)`