Question

How do you solve `15x-20y=-1` and `10y=1+5x` using substitution?

Answer 1

`x=1/5`
`y=1/5`

Explanation:

`15x-20y=-1` or `15x=20y-1`
Multipling both sides of the equation `10y=1+5x` by `3`
we get
`30y=3+15x`
or
`15x=30y-3` And we have `15x=20y-1`
`30y-3=20y-1`
or
`30y-20y=3-1`
or
`10y=2`
or
`y=2/10`
or
`y=1/5`===============Ans `1`
We have `15x=20y-1`
so
`15x=20/5-1`
or
`15x=4-1`
or
`15x=3`
or
`x=3/15`
or
`x=1/5`================Ans`2`