Calvin and Susie had some game cards at first. Calvin gave 1/4 of his cards to Susie. After that, Susie gave 1/5 of her cards to Calvin. In the end, Calvin had 45 cards and Susie had 36 cards. How many cards did Calvin have at first?
+1641 Calvin and Susie had some game cards at first. Calvin gave 1/4 of his cards to Susie. After that, Susie gave 1/5 of her cards to Calvin. In the end, Calvin had 45 cards and Susie had 36 cards. How many cards did Calvin have at first?
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Calvin's cards => x Susie's cards => y (At first)
x + y = 81
x = 81 - y
1/4(81 - y) Susie received from Calvin
1/5[y + 1/4(81 - y)] Susie gave to Calvin
4/5[y + 1/4(81 - y)] = 36 y = 33
x = 81 - 33
x = 48 Cards that Calvin had at first.
