Answer:
Linear function:
x- Independent variable 
y- Dependent variable
Step-by-step explanation:
We are given that 
Climbers start climbing at an elevation of height =5000 ft
The steady rate at which climbers start climbing=1500 ft/h
We have to find the independent variable and dependent variable.
Let time taken by climbers=x hours
In 1 hour, climbers cover distance =1500 ft 
In x hours , climber cover distance=1500x ft 
According to question 
The total distance y covered by climber in x hours

This is required linear function.
We can see that 
x does not depend on any other quantity.Therefore, x is independent variable .
When the value of x changes then the value of y is also change.
It means the value of y depends on the value of x.
Therefore, y is dependent variable.