Charlie collects rare coins. Of his display cases, 3 cases contain 15 coins each and 4 cases contain

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Charlie collects rare coins. Of his display cases, 3 cases contain 15 coins each and 4 cases contain 17 coins each. On Monday, Charlie bought 10 new coins for his collection. How many total coins does he have in his collection now?

We have cases * coins + extra coins:
3(15) + 4(17) + 10
45 + 68 + 10
123 coins