help plzzzz ill give extra points

Answer:
12x
16x, 320
20
Step-by-step explanation:
Hope this helps
Total equation ,
[tex]\displaystyle\sf\to 4x+\boxed{\sf 12}x=\boxed{\sf 320}[/tex]
[tex]\displaystyle\sf\to \boxed{\sf 16}x=\boxed{\sf 320}[/tex]
[tex]\displaystyle\sf\to x =\boxed{\sf 20}[/tex]