yenenat lemma

A plane can fly 980 miles in the same time as it takes a car to go 420 miles. If the car travels 80 mph slower than the plane, find the speed of the plane.

A farmer needs to enclose three sides of a field with a fence (the fourth side is a river). The farmer has 32 feet of fence and wants the field to have an area of 128 sq-feet. What should the dimensions of the field be? (For the purpose of this problem, t...