Let the man's stride be x cm.
Then the wife's stride is (x - 15) cm.
The distance that they cover is 30 m = 3000 cm.
The number of steps taken by man in 30 m is 3000/x.
The number of steps taken by wife in 30 m is 3000/(x - 15).
As the man covers 30 m in 10 steps less than his wife, we get the equation:
3000/(x - 15) - 10 = 3000/x
3000x - 10x(x-15) = 3000(x -15)
3000(x - x + 15) - 10(x2 - 15x) = 0
3000 * 15 = 10(x2 - 15x)
x2 - 15x - 4500= 0
x2 - 75x + 60x - 4500 = 0
x(x - 75) + 60(x - 75) = 0
(x - 75)(x + 60) = 0
x = 75 cm
x - 15 = 60 cm
Thus, the man's stride is 75 cm and the wife's stride is 60 cm.
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