Petrus shared his birthday cake with 5 of his friends.He gave Sandy 1/8,Mary and Paul1/10 each.He gave Jack 1/5 and Sandra 3/20.What fraction of the cake had he left.

Answer 1

1/8 = 5/40
1/10 = 4/40
1/5 = 8/40
3/20 = 6/40
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. . . 23/40 >>>> eaten

40/40 - 23/40 = 17/40 left