Use the additive inverse to find -492.89- -871.78.

To find the sum of -492.89 and -871.78, we can rewrite the second number using its additive inverse:

-492.89 - (-871.78)

Using the rule of subtracting a negative number (which is the same as adding its positive value), we can rewrite the expression as:

-492.89 + 871.78

Now we can perform the addition:
= 378.89

Therefore, -492.89 - (-871.78) is equal to 378.89.

To find the sum of -492.89 and -871.78 using the additive inverse, we can change the operation and rewrite it as the sum of -492.89 and the additive inverse of -871.78. The additive inverse of a number is simply the negative of that number.

The additive inverse of -871.78 is 871.78. So, we can rewrite the expression as:

-492.89 + 871.78

To add these two numbers, we align the decimal points and perform the addition:

-492.89
+ 871.78
___________
378.89

Therefore, -492.89 - -871.78 is equal to 378.89.