Please answer the following questions:
A football shoe and a ball cost 110 Euro together. The shoe costs 70 Euro more than the ball. How much costs the ball?
5 machines need 5 minutes to produce 5 keyboards. How long would 80 machines need for 80 keyboards?
An IT-company offers you storage space. Every day your volume of data doubles. If it would need 20 days to max out the provided space, how long would it take to max out half of the space?