Question

perimeter of a jogging track is 300 m if the length of the track is 100m find the width of the track

Answer 1

Perimeter of jogging track= 2(l+b)
300m= 2(100+x)
300/2=100+x
150=100+x
150-100=x
X=50
Width of track is 50m

Answer 2

Perimeter=300m
Length=100m

or 2(l+b)=300
    2(100+b)=300
    200 + 2b=300
    2b=100
    b=50

Therefore breadth of track is 50 meters.
Hope it helps...
Cheers! :D