A bicyclist was going from point A to point B at a speed of 12 km/hr. On the way back he increased his speed to 18 km/hr and covered the distance in 15 minutes less. What is the distance between point A and point B?.

9 km

Step-by-step explanation:

Let's say he takes x hours going from point A to point B and y hours going back

y = x - 15 minutes

note that x is in hours, so we must convert

15 minutes = 1/4 of an hour = 0.25 hours

y = x - 0.25 hours

distance = speed * time

on the way there:

distance = 12 km/hr * x

on the way back:

distance = 18 km/hr * y

plug y = x-0.25 hours into the way back equation

distance = 18 km/hr * (x-0.25 hours)

distance = 12 km/hr * x

the distance is the same, so set these equations equal to each other

12 km/hr * x = 18 km/hr * (x-0.25 hours)

12 km/hr * x = 18 km/hr * x - 4.5 (km/hr * hours) = 18 km/hr * x - 4.5 km

subtract 18 from both sides to put all variables on one side

-6 km/hr * x = -4.5km

divide both sides by -6 km/hr to isolate x

x = 4.5/6 hours = 3/4 hours = 45 minutes

distance = 12 km/hr * 3/4 hours = 9 km

i dont know

step-by-step explanation: