Question

How do you solve the following system: #-2x + 5y = 20, 2x +5y = 5 #?

Answer 1

`-2x+5y=20-----(1)`
`2x+5y=5------(2)`
By adding eqn (1) and eqn(2) we get
`-cancel2x+5y+cancel2x+5y=20+5`
`=>10y=25`
`=>y=25/10=5/2`
putting the value of y in eqn(2)
`2x+5*5/2=5`
`=>2x=5-25/2=-15/2`
`=>x =- 15/4=-3 3/4`