Final answer:
The algebraic expression for 'only fourth of the difference of 5 and a number', with the number being x, is (5 - x) / 4.
Step-by-step explanation:
To represent the sentence 'only fourth of the difference of 5 and a number' as an algebraic expression where the number is represented by the letter x, we first define the difference of 5 and a number, which is 5 - x. Then, to find only a fourth of this difference, we must divide that expression by 4. The complete algebraic expression is (5 - x) / 4.