To find the equation that does not belong with the other three we have to solve each equation.
Given the equation:

Dividing by 4 at both sides:

7:


Simplifying on the left:

10:

:


27:


4 :

5

In consequence, the equation that does not belong with the other three is:

because its solution, 4, is different from the solution to the other equations (2).
If we change the 5 in the equation by a 10 and solve the equation we get:

And now the equation (with a 10) belongs with the other three