Adding whole numbers and fractions

Question

You need 10 liters of water to fill a tank. You put 3 11/12 liters in, your friend added 1 2/5 liters. How much more water is needed to fill the tank?

Answer 1

3 11/12 + 1 2/5 = 3 + 1 + 11/12 + 2/5 = 4 + 55/60 + 24/60 = 4 + 79/60 = 5 + 19/60

10 - 5 - 19/60 = 5 - 19/60 = 4 41/60 must be added.