Write an equation for which 3 is a solution ?

Hint: We are asked for an equation with a solution 3 . From this we can get that the multiples of the equation $x - 3 = 0$ gives the solution 3

Complete step-by-step answer:
We are given that 3 is a solution of the equation
Since 3 is the solution we can write it as
$ \Rightarrow x = 3$
Now bringing the 3 to the other side we get a linear equation whose solution is 3
$ \Rightarrow x - 3 = 0$
Hence the multiples of this equation yields the solution 3
Hence the required equation
$ \Rightarrow k\left( {x - 3} \right) = 0$, where $k \in N$

Note: A linear equation is an algebraic equation in which each term has an exponent of one and the graphing of the equation results in a straight line. Standard form of the linear equation is y = mx + b. Where, x is the variable and y, m, and b are the constants.