Question 193277
solving
1) x+4y=100
2)x+2y=10
subst (1)-(2)
2y=90
y=45
subst  in  (2)
x+2(45)=10
x+90=10
x=-80
check
(1)  (-80)+4(45)=-80+180=100,,,ok
(2) (-80)+2(45)=-80+90=10,,,ok