A coffee shop uses 4 liters of milk every day. a. If there is 15 L of milk in the fridge, after how many days will more milk need to be purchased?
b. If only half as much milk is used each day, after how many days will more milk need to be purchased?

Long division setup showing an incomplete calculation. 12 is in the divisor, 6839 is in the dividend, and 5 hundreds and 6 tens is written in the quotient. 6000 is subtracted from 6839 to give 839. an unknown value represented by a box is being subtracted from 839. what number should be placed in the box to complete the division calculation?