Let price of a pen=x
Price of book =y
5 pen and 1 book cost 225
Ie,
5x+y=225 _______eqn (1)
Cost of 10 pen equals 1 book.
Ie,
10x =y________eqn (2)
put value of y in eqn (1)
5x+y=225
5x +10x =225
15 x =225
x =225/15
=15
Cost of pen =15
Now
Cost of book =10x
=10×15
=150
cost of 3 pen and 2 book
=3x +2y
=(3×15) + (2×150)
=45 +300
=345