Answer:
The required equation tells how far they'll be from home t hours later is

Explanation:
Given : Suppose a family starts out 50 miles from home at time t = 0. They travel away from home at a constant speed of 45 miles an hour.
To find : What is the equation that tells you how far they'll be from home t hours later?
Solution :
Let d is the distance covered in time t at a speed s
The relation between them is

They travel away from home at a constant speed of 45 miles an hour.
The distance covered is

The family starts out 50 miles from home at time t = 0.
So, The total distance they covered is

Therefore, The required equation tells how far they'll be from home t hours later is
