 <translate> Reconstruct a question, answer pair from this explanation: If each of the 20 customers bought 15 marbles, then they bought 20 * 15 = 300 marbles in total from Mr Julien's store. The number of marbles remaining in the store is 400 - 300 = 100 marbles.
 <yor> Ṣàtúnṣe ìbéèrè kan, dáhùn tọkọtaya láti inú àlàyé yìí: Bí ẹnìkọ̀ọ̀kan àwọn oníbàárà 20 bá ra ìrì 15, nígbà náà wọ́n ra ìrì 20 * 15 = 300 ní àpapọ̀ láti inú ilé ìtajà Ọ̀gbẹ́ni Julien. Nọ́mbà àpá tó kù nínú ilé ìtajà náà jẹ́ 400 - 300 = 100 àpá. 