Here's a puzzle for you to solve.

Fred
and Frank are two fitness fanatics on a run from A to B. Fred runs half
the way and walks the other half. Frank runs for half the time and
walks for the other half. They both run and walk at the same speeds. Who
finishes first?

Puzzle from

Fawn Nguyen's puzzles and brainteasers, set 13
Here's one possible way to solve it. Choose some easy numbers for the distance they travel, for the speeds, and for the time in case of Frank.Then just calculate!

Let's say they run 10 miles per hour and walk 5 miles per hour. Let's also say the distance from A to B is 20 miles.

Fred runs half the way. So, Fred runs 10 miles = 1 h, and he walks 10 miles = 2 h. So he takes a total of 3 hours.

Frank runs half the time and walks half the time. Now, we don't know the time, so let it be t. We can write an equation about the total distance:

(distance running) + (distance walking) = 20 miles

(1/2t) * 10 + (1/2t) * 5 = 20

5t + 2.5t = 20

7.5 t = 20

t…