Question

You and a friend decide to take a road trip. You drive an average speed of 70 mph and your friend drives an average of 75 mph. You want to drive at least 500 miles per day. You also plan to spend no more than 10 hours driving each day. Which of the following is a system of linear inequalities that represents this situation? Let x = number of hours you drive and let y represent the number of hours your friend will drive.

Answer 1

Given:

your speed = 70 mph

Your friend's speed = 75 mph

You want to drive at least 500 miles per day.

You also plan to spend no more than 10 hours driving each day.

To find:

The system of linear inequalities that represents this situation.

Solution:

Let x be the number of hours you drive and let y represents the number of hours your friend will drive.

You also plan to spend no more than 10 hours driving each day.

`x+y\leq 10`

Your speed is 70 mph and your friend's speed is 75 mph. So, the distance covered in x and y hours are 70x miles and 75y miles respectively.

You want to drive at least 500 miles per day. So, the total distance must be greater than or equal to 500.

`70x+75y\geq 500`

`5(14x+15y)\geq 500`

Divide both sides by 5.

`14x+15y\geq 100`

Therefore, the required system of inequalities has two inequalities
`x+y\leq 10` and
`14x+15y\geq 100`.