Alex was biking along a 48 mile trail. First half of the time he was biking twice as fast as the second half of the time. If he spent 4 hours on the road, how fast was he biking at first?

Answer 1

Distance = (Rate)(Time)

Let x = speed for the last two hours

So, 2x = speed for the first two hours

(2x)(2) + (x)(2) = 48

6x = 48 So, x = 8 mph

Speed for first half of the trip = 2x = 16 mph

Answer 2

48=4(2x+x)

=12x

x=4; starting=8