Question 1055734
x+y=20
25x+15y=430.
Multiply the top equation by -15
-15x-15y=-300
25x+15y=430
add them and the y disappear
10x=130
divide by 10
x=13
Put into first equation and 13+y=20; y=7
Check with the second equation
25(13)+15(7)=325+105=430
(13,7)
Note, you could multiply the first equation by -25, and then when you added, you would eliminate the x s and get the y.  You eliminate whatever appears to be easier.