SOLUTION: Mike rode his bike 4 miles from his house to his friend's house. from there, they took a car and drove 25 miles to a concert. Assume the average rate of the car was 45 mph faster t

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Question 849915: Mike rode his bike 4 miles from his house to his friend's house. from there, they took a car and drove 25 miles to a concert. Assume the average rate of the car was 45 mph faster than the average rate of his bike.
A. Express the total time required to complete the 29 mile trip (bike and car) as a function of the rate x of the bike.
B. Find algebraicallu or graphcally the rate of the bike if the total time of the trip was 1 hour and 45 mins.
Answer by josgarithmetic(39630) About Me  (Show Source):
You can put this solution on YOUR website!
_________________speed____________time__________distance
Bike______________r______________________________4
Car______________r+45____________________________25


Fill the time slots using T=D/R from the basic travel uniform rate equation

_________________speed____________time__________distance
Bike______________r_______________4/r_____________4
Car______________r+45_____________25/(r+45)_______25


Question A Total time, %284%2Fr%29%2B25%2F%28r%2B45%29.

Question B: If you want the time to be 1 hour 45 minutes, this is 1%263%2F4 hours. Solve the equation, %284%2Fr%29%2B%2825%2F%28r%2B45%29%29=1%263%2F4.
You start this way:
LCD is r%28r%2B45%29.

4%28r%2B45%29%2B25r=%287%2F4%29%28r%5E2%2B45r%29
16%28r%2B45%29%2B100r=7%28r%5E2%2B45r%29
.
.