Problema Solution
Kali left the store two hours before Stefan. They drove in opposite direction Stefan drove at 47 km/h for three hours after this time they were 506 km apart. Find Kali's speed
Answer provided by our tutors
let
v1 = Kali's speed
v2 = 47 km/h Stefan's speed
t1 = 3 + 2 = 5 hr the time that Kali drove (2 hours more than Stefan)
t2 = 3 hr the time that Stefan drove
d = 507 km the distance between them
since distance = speed*time the total distance they drove will be d = 507 km that is:
v1*t1 + v2*t2 = d
5*v1 + 47*3 = 507
by solving we find:
v1 = 73.2 km/h
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Kali's speed was 73.2 km/h.