Let the speed of the joker initially be x mi/hr
after reduction, the new speed will be: (x-1) mi/hr
but
time=(distance)/(speed)
hence :
Total time taken will be:
4/x+5/(x+1)=41/20
solving for x we get:
x=21.585 mi/hr
thus the initial speed was 21.585 mi/hr after reduction the new speed was 20.585 mi/hr
I think it’s one half 1/2
what is your clear question? it lacks some details
