What is to be added to 74.5 to get 91?

Answer

To solve the question "What is to be added to 74.5 to get 91?", we can follow these steps:

### Step-by-Step Solution:

1. **Identify the equation**: We need to find a number (let's call it \( x \)) that, when added to 74.5, equals 91. This can be expressed as:
\[ 74.5 + x = 91 \]

2. **Rearrange the equation**: To isolate \( x \), we can subtract 74.5 from both sides of the equation:
\[ x = 91 - 74.5 \]

3. **Perform the subtraction**: Now, we need to calculate \( 91 - 74.5 \):
- First, align the numbers by their decimal points:
```
91.0
- 74.5
```
- Subtract the numbers:
- Starting from the right, we subtract 5 from 0. Since we can't do that, we need to borrow 1 from the 1 in the tenths place, making it 0 and turning the 0 in the units place into 10.
- Now, we have \( 10 - 5 = 5 \).
- Next, we subtract the whole numbers: \( 9 - 7 = 2 \).
- So, \( 91 - 74.5 = 16.5 \).

4. **Conclusion**: Therefore, the number that needs to be added to 74.5 to get 91 is:
\[ x = 16.5 \]

### Final Answer:
The number to be added is **16.5**.