Question

Five litres of milk can be exchanged for one old book. How much milk can you get for four old books?

Answer 1

Given,
Amount of milk for one old book = 5 litres
Number of old books = 4
Amount of milk for four old books = 4 $\times$ Amount of milk for one old book
= 4 $\times$ 5 litres
= 20 litres

Thus, 20 litres of milk can be exchanged for 4 old books.