Level 2
Tesssa has $16 worth of coins. 12 of them are 50¢ coins and 5 of them are 20¢ coins. The rest are $1 coins. How many coins does Tesssa have altogether?
2 m
Level 3
An empty tank measures 50 cm by 20 cm by 35 cm. Water flows into the tank from Tap A at a rate of 25 ℓ per minute. At the same time, water drains from the tank from Tap B at a rate of 18 ℓ per minute. How long would it take to completely fill the tank?
3 m