# One car travels at 10 miles an hour and another travels at 5 mph. in how many hours will they be 45 miles apart?

Oct 18, 2016

$t = 3 \text{ hours or 9 hours}$

#### Explanation:

$\text{area under graph gives displacement...}$

$\text{if cars move at the same direction :}$

$10 \cdot t - 5 \cdot t = 45$

$5 t = 45$

$t = \frac{45}{5}$

$t = 9 \text{ hours}$

$\text{if cars move at opposite direction}$

$10 t + 5 t = 45$

$15 t = 45$

$t = 3 \text{ hours}$