Question

You gave yourself 35 min to drive 23 miles to the party, but you are caught in traffic and average 20 miles/hour for the first 15 min. What is your average speed for the rest of your journey to the party.

I am lost any help in approaching the problem wouldbe great.

Answer 1

distance=speed*time
23=20*15/60 + second speed*20/60
solve for second speed

Answer 2

distance = rate x time
15 min = 15/60 = 1/4 hr.
distance = 20 mi/hr x 1/4 hr 5.0 miles.

How much time is left? 35 minutes-15 minutes = 20 minutes = 1/3 hr (that's 20/60 = 1/3 hr).
How much distance is left? 23 miles -5 miles = 18 miles.
d=r*t
18 = r*1/3
Solve for rate in miles/hr.
18 miles = rate * 1/3