Answer:
The answer is 110 degrees C.
Explanation:
The melting point of substance X is -20 degrees Celsius and the boiling point is 90 degrees Celsius.
To find the difference between the degrees, we will subtract the values.
So, the difference between these points will be =
![90-(-20)](https://img.qammunity.org/2019/formulas/mathematics/high-school/mzk6l562lcoh296nwpw2tjezccjj06px4n.png)
=
![90+20=110](https://img.qammunity.org/2019/formulas/mathematics/high-school/4iov2u0bp3nuixwq744odg6h5100iwxur3.png)
The answer is 110 degrees C