Question 734088
X+Y=20
X=20-Y
3X+8Y=110
3(20-Y)+8Y=110
60-3Y+8Y=110
5Y=110-60
5Y=50
Y=50/5
Y=10 NUMBER OF 8 DOLLAR(?) BOOKS.
X=20-10=10 NUMBER OF 3 DOLLAR (?) BOOKS.
PROOF:
3*10+8*10=110
30+80=110
110=110