Answer:
See below.
Explanation:
We want to show that:
![10x+30x=40x](https://img.qammunity.org/2021/formulas/mathematics/high-school/irdqbkivngtefo014hdgmgvon3x8wguzry.png)
Using the distributive property.
To do so, let's take a look at our original expression:
![10x+30x](https://img.qammunity.org/2021/formulas/mathematics/high-school/hufcxkybuvc2f1feiuv5tb6i62r4n79tz3.png)
From here, we can factor out a x. In other words, we un-distribute, the reversing the distribute property. This yields:
![=x(10+30)](https://img.qammunity.org/2021/formulas/mathematics/high-school/z3zqigtwwzoxhd0jegjeor05v6a36uutzu.png)
If we distribute again, we'll get the same thing.
From here, let's add within the parentheses...
![=x(40)](https://img.qammunity.org/2021/formulas/mathematics/high-school/ategkv1p5ml2jskn164aqkdpwyablrngmb.png)
And multiply:
![40x](https://img.qammunity.org/2021/formulas/mathematics/high-school/9b95cfq8mb3v5a62id6o1xlgylb8sgjvwx.png)
This gets the desired result.
And we're done!