SOLUTION: Rachel allows herself 1 hr to reach a sales appointment 50 miles away. After she has driven 30 miles, she realizes that she must increase her speed by 15 mph in order to get there

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Rachel allows herself 1 hr to reach a sales appointment 50 miles away. After she has driven 30 miles, she realizes that she must increase her speed by 15 mph in order to get there       Log On


   

Question 242751: Rachel allows herself 1 hr to reach a sales appointment 50 miles away. After she has driven 30 miles, she realizes that she must increase her speed by 15 mph in order to get there on time. What was her speed for the first 30 miles?
Answer by jojo14344(1513) About Me  (Show Source):
You can put this solution on YOUR website!


Basic Eqn : Speed = Distance / Time

Remember, Rachel Speed should be 50 mi/hr ---> S%5B1%5D

After travelling 30 miles in t time ----> S%5B2%5D, she increased by 15mi/hr -----> S%5B3%5D

Putting the scenario into eqn:
S%5B1%5D=S%5B2%5D%2BS%5B3%5D ----------> Working Eqn

50%28mi%2Fhr%29=30%28mi%2Ft%29%2B15%28mi%2Fhr%29
%2850-15%29%28mi%2Fhr%29=30%28mi%2Ft%29
%2835%28mi%2Fhr%29%29%28t%29=30mi --->
red%28t=0.857hr%29 ---> subst. to S%5B2%5D

So, her speed for the 1st 30 miles = 30mi%2F0.857hr=red%2835%28mi%2Fhr%29%29, ANSWER

Check, go back Working Eqn:
50%28mi%2Fhr%29=35%28mi%2Fhr%29%2B15%28mi%2Fhr%29
50%28mi%2Fhr%29=50%28mi%2Fhr%29

Thank you,
Jojo