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【OG20-P274-248题】
Last semester, Professor K taught two classes, A and B. Each student in class A handed in 7 assignments, and each student in class B handed in 5 assignments. How many students were in class A(1) The students in both classes combined handed in a total of 85 assignments.(2)There were 10 students in class B
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条件1:7A+5B=85,A=5或A=10都满足,不充分
条件2:B=10,A无法求,不充分
结合:A=5,B=10,充分
题目讨论 (1条评论)

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大宝宝
条件1,7A+5B=85:因为85是5的倍数,因此A也要是5的倍数(因为7不是5的倍数),可得A=5或10.不充分,取值不唯一 条件2,B=10,A未知,不充分 条件1+条件2,B=10的时候,7A+50=85,A=5,充分
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0 回复 2018-07-11 13:41:05
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sabina回复大宝宝
那这道题是错了吗
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0 回复 2018-09-27 16:18:25
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