SOLUTION :
Let the original speed y km/ hr and total time taken be x h
Distance = xy
[ Distance = time × speed]
(y + ½) (x - 1) = xy
xy - y + x/2 - ½ = xy
x/2 - y = ½ ………………(1)
[Distance covered in each case is same]
(y -1) (x + 3) = xy
xy + 3y -x -3 = xy
-x + 3y = 3……………..(2)
Multiply equation 1 by 3 ,
3x/2 - 3y = 3/2…………(3)
On adding eq 2 and 3,
-x + 3y = 3
3x/2 - 3y = 3/2
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-x +3x/2 = 3/2 +3
(-2x + 3x)/2 = (3+6)/2
x/2 = 9/2
x = 9
On Putting x = 9 in eq 2
-x + 3y = 3
-9 + 3y = 3
3y = 3 +9
3y = 12
y = 12/3
y = 4
Distance covered by man = xy = 9 × 4 = 36 km
Original speed of walking = y = 4 km/h
Hence, the Distance covered by man is 36 km & Original speed of walking is 4 km/h.
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