What is 18.75 divided by 1 and 1/2

Jack lives on a farm and has a large backyard. the area of his rectangular backyard is of a square mile. if the width of the yard is of a mile, what fraction of a mile is the length of the rectangular backyard?

How to do this , and can some one explain

Given the following linear function sketch the graph of the function and find the domain and range. ƒ(x) = -5x + 4