Answer:
[tex]\boxed{ \text{8 p.m.}}[/tex]
Step-by-step explanation:
First, we must plot the graph of your system of equations (see below).
The two lines cross at (12, 360).
Thus, machine A had been going for 12 h. It started at 8 a.m., so it ended at 8 p.m.
Both machines had made 360 ft of wire by [tex]\boxed{ \text{8 p.m.}}[/tex]
Check:
360 = 30 × 12 360 = 40(12 – 3)
360 = 360 360 = 40 × 9
360 = 360
OK.
