Two trucks leave a warehouse at the same time. One travels due west at an average speed of 49 miles per hour, and the other travels due east at an average speed of 63 miles per hour. After how many hours will the two trucks be 840 miles apart?

7.5 hours

Way Number One:

This way uses critical thinking

     These two trucks are traveling in opposite directions (West and East). One truck moves 49 miles every hour, and the other moves 63 miles per hour. Since they are traveling in opposite directions, we do not have to worry about angles or use a distance formula.

     Every hour one truck moves 49 and the other 63. So, if we add 49 to 63 we will get their distance apart after one hour.

-> 49 + 63 = 112 miles

     Now, we want to know how long it will take for them to be 840 miles apart. We can divide 840 by 112 to see how many hours it will take, because every hour the trucks become 112 miles farther apart.

-> 840 / 112 = 7.5 hours

Way Number Two:

This way uses a graphing calculator

     We can turn the distance traveled by each truck into equations. Let y be miles traveled and x be time spent.

First truck, y = 49x

Second truck, y = 63x

     We know their distance apart will be the miles traveld added together, so y = 63x + 49x. Our answer will be x when y is equal to 840. After graphing, we get the point of (840, 7.5)

-> See attached

Have a nice day!

     I hope this is what you are looking for, but if not - comment! I will edit and update my answer accordingly.

- Heather

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step-by-step explanation: