Answer:
Brian's rate is 15 km/hr
Adrian's rate is 16 km/hr
Step-by-step explanation:
Let r = Brian's rate
r + 1 = Adrian's rate
4/r = Brian's time
4/(r + 1) = Adrian's time
The difference in times is 1 min = 1/60 hr
[tex]\frac{4}{r} - \frac{4}{r + 1} = \frac{1}{60}[/tex] LCD = 60r(r + 1)
4(60)(r + 1) - 4(60)r = r(r + 1)
240r + 240 - 240r = [tex]r^{2}[/tex] + r
[tex]r^{2}[/tex] + r - 240 = 0
(r - 15)(r + 16) = 0
r = 15 or r = -16
Since the rate cannot be negative, Brian's rate is 15 km/hr and Adrian's rate is 16 km/hr
