Hi, 

Let x represent the speed of person walking, then 2x would be the speed of the bicyclist

question states

x + 2x = 21mph

solve for x

3x = 21mph

x = 7mph,  the speed of the person walking 

RELATED QUESTIONS

A Toyota Camry is traveling twice as fast as a Dodge truck. If their combined speed is... (answered by Fombitz)

A car is traveling twice as fast as a truck. If their combined speed is 105 miles per... (answered by rfer)

Jenny can run 2 miles per hour more than twice as fast as bob can walk. if bob can walk 3  (answered by addingup,ikleyn)

You and a friend are 4.5kilometers away from each other. Walking toward each other, the... (answered by lwsshak3)

How do I set this up as an equation and explain it to my child?

You jog at a speed of... (answered by ewatrrr,stanbon)

word problem probably a proportion d=rt I am stuck setting it up.

As part of an... (answered by stanbon,DrBeeee)

The speed of a bicyclist is 10 mph faster than the speed of a jogger. If the bicyclist... (answered by josgarithmetic)

a bicyclist completesa 100-mile race in 3 hours 45 minutes. What is the average speed, in  (answered by stanbon)

Can anyone help me solve this Im stuck

a fisherman is traveling on Pearl River took... (answered by josmiceli)