7 liters of milk and 3 litres of water is mixed in an
empty bucket 'P. In other empty bucket 'Q' six liters of milk is mixed in 1 liter of water 3 liter of mixture 'P and 4 liters of mixture from bucket 'Q' are mixed in an empty bucket 'R', What is the quantity of water (in liters) in bucket 'R' ?
