x+y=25
4200x+3100y=100000
3100(x+y)+1100x=100000
77500+1100x=100000
1100x=22500
x=225/11
y=25-225/11=50/11
x+y=25
3700x+3100y=100000
3100(x+y)+600x=100000
77500+600x=100000
600x=22500
x=75/2
y=25-75/2=-25/2
x+y=25
4200x+3100y=100000
3100(x+y)+1100x=100000
77500+1100x=100000
1100x=22500
x=225/11
y=25-225/11=50/11
x+y=25
3700x+3100y=100000
3100(x+y)+600x=100000
77500+600x=100000
600x=22500
x=75/2
y=25-75/2=-25/2