Answers

2015-11-15T14:45:02+05:30
Daniel.

On the way there Kevin drove 90 miles, and on the way back drove the (total distance - 100 miles).
On the way Daniel drove the (total distance - 90 miles), and on the way back drove 100 miles.

So Kevin drove 90 + total - 100 = total - 10.
And Daniel drove total - 90 + 100 = total + 10.

So Daniel drove 20 miles more than Kevin. QED
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2015-11-15T15:30:18+05:30
On the way there Kevin drove 90 miles, and on the way back drove the (total distance - 100 miles).
On the way, Daniel drove the (total distance - 90 miles), and on the way back drove 100 miles.

So Kevin drove 90 + total - 100 = total - 10.
And Daniel drove total - 90 + 100 = total + 10.

So Daniel drove 20 miles more than Kevin.

Hope this helped you
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