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Find the **least** value of x which satisfies the equation 4x = 7 (mod 9)

A. 7

B. 6

C. 5

D. 4

**Comments**

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4x = 7

divide both sides by 4

x = 7/4 = 1.75

But in linear congrugrence, negative or decimal values are not allowed, so, we add 9 to the initial equation (because it's in mod 9)

4x = 7 + 9

4x = 16

divide both sides by 4

x = 16/4

x = 4

**Ans D**

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