The additive identity of $13$ is _____.

$-80÷$ _____ $=5$

The multiplicative inverse of $5$ is _____.

The integer that is its own additive inverse is

Each pentagon shows the temperature of a city in degrees celsius $\left(°\mathrm{C}\right)$ from Monday to Friday. Add the temperatures and write the sum in the centre of each pentagon. 

 

$23\times 10-23\times 7=$_____