Answer:
1.
![3 (20+4x)](https://img.qammunity.org/2022/formulas/mathematics/high-school/kplxyua0h9amkxrf5mpj5mrfxzgptc5mxh.png)
2.
![60 + 12x](https://img.qammunity.org/2022/formulas/mathematics/high-school/grps71iu6sx60mwkoxuyah92eyhsckzd5d.png)
Explanation:
1. Let's just focus on one person at the moment. One of the friends bought a single shirt for $20, and 4 shirts that cost x dollars. Therefore, a single person's expense can be shown as:
![20 + 4x](https://img.qammunity.org/2022/formulas/mathematics/high-school/nvfca6ppqe5hkti6qnhvo6zk81w1xadokt.png)
Where x is the number of shirts the person bought.
Each of the three friends had the exact same expenses too, so we multiply this by three:
![3 (20+4x)](https://img.qammunity.org/2022/formulas/mathematics/high-school/kplxyua0h9amkxrf5mpj5mrfxzgptc5mxh.png)
2. Simplifying the above equation just means multiplying each term in the parentheses by the 3 outside it, so 3 times 20 is 60, and 4x time 3 is 12x. Therefore, the simplified expression is:
![60 + 12x](https://img.qammunity.org/2022/formulas/mathematics/high-school/grps71iu6sx60mwkoxuyah92eyhsckzd5d.png)
Hope this helps!