Ricky can ride 17 km on his bike in the same length of time ha can walk 9 km. if his riding speed is 4 kph faster than his walking speed how fast does he walk

Distance=speed times time

if they take the same time, we cal the time, t

b=bike speed

w=walking speed

bikedistnace=17=bt

walkdistance=9=wt

b is 4 more than w

b=4+w

we have

17=bt

9=wt

b=4w

ok so

multiply first equation by 9 and 2nd by 17

153=9bt

153=17wt

set equal

9bt=17wt

divide both sides by t

9b=17w

sub b=4+w for b

9 (4+w) = 17w

distribute

36+9w=17w

minus 9w both sides

36=8w

divide both sides by 8

4.5=w

he walks 4.5kph