#### Answer

$x+1=6$

#### Work Step by Step

One way to construct a linear equation in x whose only solution is 5 is to write an equation that has a variable and a constant on one side and a constant on the other.
For example, consider the equation $x+1=6$. By subtracting 1 from both sides, we can see that the only solution is $x=5$.
This equation has a variable and a constant on the left side and a constant on the right side, where the constants differ in value by 5. Therefore, by inserting $x=5$ into the right side, we are able to make the left side have the same value as the right side.