Let the distance cover by the person on first day = n
Succeeding day = n-1
Next day = n-2
And so on.........
Therefore
He covered n+(n-1)+(n-2)+(n-3) miles from rugby to London in four days.
That is 4n-6 ------------(1)
Now it took him 5 days to return back,
The distance covered by him in 5 days = (n-4)+(n-5)+(n-6)+(n-7)+(n-8) => 5n-30 -----------(2)
Distance between two cities is same
4n-6 = 5n-30
24 = n
So the person cover 24 miles on first day.
He covered 4n-6 miles to cover the distance between rugby and London.
Substituting value;
4(24)-6 = 96-6 = 90 miles.(LHS)
Also,
5(24)-30 = 120-30 = 90 miles.(RHS)
Answer is D
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