WAEC - Mathematics (2016 - No. 38)
If 20(mod 9) is equivalent to y(mod 6), find y.
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Explication
First, reduce 20(mod 9) to its simplest form in mod 9; 9 x 2 + 2 = 2(mod 9)
If 2(mod 9) y(mod 6), then y = 2 by comparism
If 2(mod 9) y(mod 6), then y = 2 by comparism