The function, f(x)=70n-400, models the profit the instructor of guitar class per

6 students.

Step-by-step explanation:

We have been given a function that models  the profit the instructor of guitar class per month, where n is the number of students enrolled in the class.

We can see that 400 represents the amount of fixed expenses to run the guitar class by instructor and 70 represents the amount charged by instructor per student.

To make an profit the amount collected from n students minus the fixed charges must be greater than 0. So we can set up an inequality to solve for n as:

Dividing both sides of our inequality by 7- we will get,

Since 0.714 of a students can not be enrolled, so we will round up our answer.

Therefore, 6 students must be enrolled in the class for the instructor to make a profit.

Step-by-step explanation:

Observe the graph provided in the exercise.

The y-axis represents the plane's elevation in meters and the x-axis represents the time in seconds.

Notice that at 0 seconds the elevation of the plane is . Based on the graph, each the elevation of the plane decreases

The plane lands when the elevation is 0 meters and this happens when the line shown in the graph intersects the x-axis.

Therefore, the time took the plane to land is: