Answer :
55x+90y=1900
x+y=25, x=25-y
55(25-y)+90y=1900
1375-55y+90y=1900
35y=525
y=15
So it is 15 for the 90$ and 10 for the 55$
x+y=25, x=25-y
55(25-y)+90y=1900
1375-55y+90y=1900
35y=525
y=15
So it is 15 for the 90$ and 10 for the 55$