Below is an instruction that describes a task. Write a response that appropriately completes the request in Swahili. Please answer in Swahili.

### Instruction:
Mr Julien's store has 400 marbles remaining after the previous day's sales. Twenty customers came into the store, and each bought 15 marbles. How many marbles remain in the store?

### Response:
 Ikiwa kila mmoja wa wateja 20 alinunua mabulinge 15, basi walinunua jumla ya mabulinge 15*20=<<300=300>>300 kutoka duka la Bwana Julien.
Idadi ya mabulinge yaliyosalia dukani ni 400-300=<<400-300=100>>100 mabulinge.