Level 2
The mass of Box X is 140 kg. The mass of Box Z is 20 kg more than the mass of Box X. The mass of Box Y is 50 kg less than the mass of Box Z. What is the mass of Box Y?
Level 3
There were 130 boys and 25 more girls than boys at a concert. There were also 90 more adults than boys. How many people were at the concert altogether?