Rihan Ride his bike from his School to the Bank and back to School with a total distance of 120 km. The bike’s speed while returning was 3 km/hr slower than the speed while going to the Bank. If the total driving time was 9 hours, what was the speed of the bike while going to the Bank?
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Answer:
15km/h
Step-by-step explanation:
Let speed while going to bank= x km/h
Therefore, speed while returning = (x+3)km/h
One way distance from school to bank Or bank to school= 120km/2= 60km
According To the Question
60/x + 60/(x+3) = 9 hours
60x + 180 + 60x= 9x² + 27x
9x² + 27x - 120x -180=0
3x² - 31x -60=0
3x² - 36x + 5x - 60 = 0
3x(x - 12) + 5(x - 12) = 0
(x - 12)(3x + 5) = 0
By zero product rule,
x = 12,-5/3
as x can not be -ve x= 12km/h
So, speed while returning= x+3= 15km/h
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