Answer:
....x= price of a workbook.
y =the price of a book
f a student spends 9600 euros on books and 8000 euros on exercise books, he will own 56 items in all.
x+y=56
9600x+8000y=17600
by substitution: y=(56-x)
replace y
9600x+8000(56-x)= 17 600
9600x-448000-8000x =17600
1600x=17600+448000
x=291
an exercise book costs $291
what's the difference between the price of a book and a workbook?
a book costs 3 times more than a workbook, a book costs 291*3=$873
difference between the price of a book and a workbook:873-291=$582