`98.76 + 24.96 + 215.005 - ? = 309.99`

Options

A. a. 28.76
B. b. 29.5
C. c. 30.0
D. d 31.5

Answer

To solve the equation \( 98.76 + 24.96 + 215.005 - ? = 309.99 \), we will follow these steps:

### Step 1: Add the numbers on the left side of the equation.
We need to calculate \( 98.76 + 24.96 + 215.005 \).

1. Align the numbers by their decimal points:
```
98.760
+ 24.960
+215.005
```

2. Add them column by column:
- Starting from the rightmost column:
- \( 0 + 0 + 5 = 5 \)
- Next column:
- \( 6 + 6 + 0 = 12 \) (write down 2 and carry over 1)
- Next column:
- \( 7 + 9 + 5 + 1 (carry) = 22 \) (write down 2 and carry over 2)
- Next column:
- \( 8 + 4 + 1 + 2 (carry) = 15 \) (write down 5 and carry over 1)
- Finally:
- \( 1 + 2 + 0 + 1 (carry) = 4 \)

So, the total is:
\[ 98.76 + 24.96 + 215.005 = 338.725 \]

### Step 2: Set up the equation to find the question mark.
We have:
\[ 338.725 - ? = 309.99 \]

### Step 3: Rearrange the equation to solve for the question mark.
To find \( ? \), we can rearrange the equation:
\[ ? = 338.725 - 309.99 \]

### Step 4: Perform the subtraction.
Align the numbers by their decimal points:
```
338.725
- 309.990
```

1. Subtract column by column:
- Starting from the rightmost column:
- \( 5 - 0 = 5 \)
- Next column:
- \( 2 - 9 \) (we need to borrow, so it becomes \( 12 - 9 = 3 \))
- Next column:
- \( 7 - 9 \) (again we need to borrow, so it becomes \( 17 - 9 = 8 \))
- Next column:
- \( 8 - 0 - 1 (borrow) = 7 \)
- Finally:
- \( 3 - 3 = 0 \)

So, the result of the subtraction is:
\[ ? = 28.735 \]

### Final Answer:
The value of \( ? \) is \( 28.735 \).

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