A horse drinks 20 litres of water per day. How many litres of water would it drink in a week?
A=7 and B=4
A=4 and B=7
A=4 and B=9
A=5 and B=7
There are 108 keys for playing music; it takes 3 seconds to listen entirely to the music made by each key. If all keys are hit in sequence after complete music made by each key, Find the total time to listen to all key sounds.