Julia ran and bikes for a total of 40 miles in 5.8 hours. Her average running speed was 5.5 mph. Her average biking speed was 13.5 mph.

Let x = total hours Julia ran

Ley y = total hours Julia biked

Use substitution to solve for x and y.SHOW ALL WORK.Round answers to nearest tenth.

- How many hours did Julia run?
- How many hours did Julia bike?

KennedyPape
Sep 11, 2018

#1**+2 **

We have that

x + y = 5.8 ⇒ y = 5.8 - x (1)

And note that rate * time = distance covered.....so..

5.5x + 13.5y = 40 (2) put (1) into (2) for y and we have

5.5x + 13.5(5.8 - x) = 40 simplify

5.5x + 78.3 - 13.5 x = 40

-8x + 78.3 = 40 subtract 78.3 from both sides

-8x = - 38.3 divide both sides by -8

x ≈ 4.8 hrs running

And y ≈ 5.8 - x = 5.8 - 4.8 ≈ 1 hrs biking

CPhill
Sep 11, 2018