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Re: Is a+b divisible by 7? [#permalink]
04 Aug 2010, 10:35
1) let a = 1, then if b = 1 we have a+b not divisible by 7. on the other hand if b =6, a+b is divisible by seven. Not Sufficient 2) Use the same argument as in 1), Not Sufficient 1 & 2) Use the same argument as in 1). Not Sufficient