Answer:
7
Step-by-step explanation:
When finding the x intercept you replace the y with 0 leaving only x=7
You find it the same way you find the y - intercept in y=mx+b.
x=21
100+3x+x-4=180
100+4x-4=180
96+4x=180
4x=180-96
4x=84
i don't know
sorry
