Round each to the nearest ten dollars, then estimate the answer.

$88.99=---dollars
+9.69=---dollars
-----------------
Total is about---Dollars.

$34.00=----dollars
-19.29=----dollars
------------------
Differences is about-----dollars.

88.99 = about 90.

9.69 = about 10.
90+10 = about $100.

Now you do the subtraction one.

88.99 roundes to 90.00 and 9.69 roundes to 100.00

10.00

To round each amount to the nearest ten dollars, you need to look at the digit in the tens place. If the digit in the ones place is 5 or greater, you need to round up. If it's less than 5, you round down.

For the first question:
- $88.99: The digit in the tens place is 8, which is greater than 5, so we round up to the nearest ten dollars. The number becomes $90.
- $9.69: The digit in the tens place is 0, which is less than 5, so we round down to the nearest ten dollars. The number remains $0.

Now, you can solve the arithmetic:
$90 + $0 = $90.

Rounding the answer to the nearest ten dollars, the total is about $90.

For the second question:
- $34.00: The digit in the tens place is 3, which is less than 5, so we round down to the nearest ten dollars. The number remains $30.
- $19.29: The digit in the tens place is 1, which is less than 5, so we round down to the nearest ten dollars. The number remains $10.

Now, you can solve the arithmetic:
$30 - $10 = $20.

Rounding the difference to the nearest ten dollars, the answer is about $20.