Perry goes for a 2​-hour trip through towns and on country roads. If she averages 55 mph on country roads and 25 mph through​ towns, and if she travels three times as far on country roads as she does through​ towns, what is the total length of her​ trip?

Respuesta :

Answer:

[tex] \frac{55x + 75 x}{1375}= 2[/tex]

[tex] 13 x = 2750[/tex]

[tex] x = \frac{2750}{13}= 211.538 mi[/tex]

and [tex] 3x = 3*211.538 = 634.614[/tex]

So then the total lenght is :

[tex] x + 3 x= 4x = 4*211.538=846.152 miles[/tex]

Step-by-step explanation:

For this case we assume that:

x (miles) represent the distance driven in town at a speed of 25 mph

3x (miles) would represent the distance for country road at a speed of 55 mph

And we know that the total time is 2hr.

Let [tex] t_1[/tex] the time for the town and [tex] t_2 [/tex] the time for the country, we can set up the following equation for the time:

[tex] t_1 + t_2 = 2[/tex]

From the definition of distance we have that D = vt if we solve for the time we got t= D/v and if we replace we got:

[tex] \frac{x}{25}+ \frac{3x}{55} =2[/tex]

And now we can solve for x like this:

[tex] \frac{55x + 75 x}{1375}= 2[/tex]

[tex] 13 x = 2750[/tex]

[tex] x = \frac{2750}{13}= 211.538 mi[/tex]

and [tex] 3x = 3*211.538 = 634.614[/tex]

So then the total lenght is :

[tex] x + 3 x= 4x = 4*211.538=846.152 miles[/tex]