Given:
A number is 400.
To find:
The additive inverse of 400.
Solution:
We know that the sum of a number and its additive inverse is 0.
If "a" is number and "b" is its additive inverse, then
![a+b=0](https://img.qammunity.org/2022/formulas/mathematics/high-school/5z92mhbbvpktdd4nlb69gpmzma68sgzcf0.png)
Let x be the additive inverse of 400. Then,
![400+x=0](https://img.qammunity.org/2022/formulas/mathematics/high-school/ug3kfo51n2gfonvwtodmm1iclx7vg22x79.png)
Subtract both sides by 400.
![400+x-400=0-400](https://img.qammunity.org/2022/formulas/mathematics/high-school/7immdjwkm667x695fnmfkiaqido2aes3sv.png)
![x=-400](https://img.qammunity.org/2022/formulas/mathematics/high-school/3t9bsmcug5m2oqs9brp252gxxr1q62sjn4.png)
Therefore, the additive inverse of 400 is
.