The value of the expression 3/8 - 1/4 is 1/8.
To find this, you must first find a common denominator, which in this case is 8. Multiply 1/4 by 2/2 to get 2/8. Now, you are able to subtract the fractions to find your answer. 3/8 - 2/8 = 1/8. Thus meaning, 1/8 is your answer.
I hope this helps!