To solve the problem of subtracting mixed measures, first, borrow one degree from the top line, converting it to minutes, resulting in 18 degrees 77 minutes 33 seconds. The next step is to subtract the second measure, 7 degrees 45 minutes 28 seconds, from this adjusted value. The subtraction can be performed by aligning the degrees, minutes, and seconds separately. After completing the subtraction, the final result will provide the difference in mixed measures. This method effectively simplifies the calculation process for mixed units.