Question

Kwan hiked up a hill at 4 km/h and back down at 6 km/h. His total time was 3 h. How long did the trip up the hill take him

Answer 1

Let t=time it took Kwan to go up the hill

Then 3-t=time it took him to go down the hill

Distance(d) equals Rate(r) times Time(t) or d=rt; r=d/t and t=d/r

distance up the hill = distance down the hill

distance up=4*t

distance down=6*(3-t)----So:

4t=6(3-t) get rid of parens (distributive law)

4t=18-6t add 6t to both sides

4t+6t=18-6t+6t collect like terms

 

10t=18 divide both sides by 10

t=1.8 hr---------------------------------time to go up the hill

3-1.8=1.2 hr-----------------------------time to go down the hill

Hope this helps