Using linear functions, it is found that the two planes will be at the same altitude in 7 minutes.
A linear function is modeled by:
[tex]y = mx + b[/tex]
In which:
For the first plane:
Hence, the equation is:
[tex]y_1(x) = 400x + 1000[/tex]
For the second plane:
Hence, the equation is:
[tex]y_2(x) = -300x + 5900[/tex]
They will be at the same altitude at the value of x for which:
[tex]y_1(x) = y_2(x)[/tex]
Hence:
[tex]400x + 1000 = -300x + 5900[/tex]
[tex]700x = 4900[/tex]
[tex]x = \frac{4900}{700}[/tex]
[tex]x = 7[/tex]
The two planes will be at the same altitude in 7 minutes.
To learn more about linear functions, you can take a look at brainly.com/question/25823744