SOLUTION: 2d+4=5 Mod 7 Find d

Question 1150444: 2d+4=5 Mod 7 Find d
Answer by ikleyn(52776) (Show Source): You can put this solution on YOUR website!
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(1)   2d + 4 = 5  mod 7  =====>


(2)   2d = 5 - 4  mod 7


(3)   2d = 1  mod 7


(4)    d = 4  mod 7      ANSWER



In this chain of equations mod 7,  only transition from (3) to (4) requires explanation.


But  2d = 1  mod 7   is the same as  2d = 8  mod 7,  which makes this transition OBVIOUS.

Solved.

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