What do the unknown factor and quotient represent?

The unknown factor represents the value of the integer we are looking in a certain equation. We usually use variables to represent the unknown factor
for example:
A, B , C , X , Y , Z or any other letters that we want to use
While quotient represents that answer we get from dividing 2 or more integers.
For example:
2x + (25 / 5), where x is the unknown factor and the answer between 25/ 5 is called the quotient.

The answer is option c.