so you have
25x+10y=24
and
x+y=20
you can eith er subsitue or add
let's add
mutliply x+y=10 by -10
-10x-10y=-200
add to first equation
25x+10y=24
-10x-10y=-200 +
15x+0y=-176
15x=-176
divide both sides by 15
x=-176/15
subsitue
x+y=20
-176/15+y=20
add -176/15 to both sides
y=476/15
solution
(x,y)
([tex] \frac{-176}{15} [/tex], [tex] \frac{476}{15} [/tex]
