Answer:
4x/9
Step-by-step explanation:
The story problem of shawn's poster length and width is the correct one
Elimination:
7x - 3y = 20
5x + 3y = 16
(add)
12x = 36
÷ 12
x = 3
(5 × 3) + 3y = 16
15 + 3y = 16
- 15
3y = 1
÷ 3
y = 1/3
Substitution:
5x + 3y = 16
- 3y
5x = 16 - 3y
÷ 5
x = 3.2 - 0.6y
5(3.2 - 0.6y) + 3y = 16
16 - 3y + 3y = 16
16 = 16
- 16
6y = 0
÷ 6
y = 0
Sorry the substitution messed up for some reason, I'll fix it after I've answered the other question
Answer:

Step-by-step explanation:
You can multiply this out to get the full equations.
It's to the 4th degree so the x on the outside has to be squared to add the fourth degree.
To get other zeros:
x + 3 = 0
x = -3
x - 4 = 0
x = 4
Hope this helped. :0)