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pit.jak is right for the 1st one.
7x+7y leaves the same remainder as 2x+2y.
Now a number is of the form 4k, 4k+1, 4k+2 or 4k+3.
Of this only ordered pairs of the form x=4k+2, y=4k or vice versa are favourable.
This gives 2*25*25 = 1250 fav pairs from 100*100 possibilities.
Hence 1/8
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Moderation Team
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