Liczby naturalne w zadaniach tekstowych

Exercise 1

In the basement there are 7 barrels full of honey. One barrel with honey weighs 60kg.
Each barrel is 50kg lighter than the honey in this barrel. Calculate the total weight
of the honey in all the barrels. 

Exercise 2

Jan is 4 years old. Tomek is twice the age of Jan. In how many years will the boys
be 80 years old together?

Exercise 3

There were 9500 spectators at a football match. 6375 of them were men. From the
remaining spectators, there were 4 times as many children as women. How many
children were there?