Subtract. Write your answer as a fraction in simplest form. \[ 3 \frac{3}{4}-\frac{7}{8}= \]

Step 1 ：Convert the mixed number into an improper fraction: \(3 \frac{3}{4} = \frac{15}{4}\).

Step 2 ：Subtract the two fractions: \(\frac{15}{4} - \frac{7}{8} = \frac{30}{8} - \frac{7}{8} = \frac{23}{8}\).

Step 3 ：The result is already in its simplest form.

Step 4 ：Final Answer: \(\boxed{\frac{23}{8}}\)