90-63.9
The subtraction of 63.9 from 90 equals 26.1.
To calculate the difference between 90 and 63.9, you need to subtract 63.9 from 90.
Step 1: Write down the problem: 90 - 63.9
Step 2: Subtract the numbers: Start with the ones place (0 - 9), which requires regrouping. Borrowing 1 from the tens place, we have 10 - 9 = 1. Then subtract the tens place (8 - 6 = 2). So, the difference is 26.1.
Therefore, 90 - 63.9 = 26.1.