Each empty white square in the grid contains one of the numbers 1, 2, 3,..., 8. Each of the horizontal and vertical equations must be true and each number must be used exactly once.

Hint: It doesn't matter how far it was to Manchester.

Answer: 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.

Puzzle 3

Exactly how many minutes is it before seven o'clock, if 40 minutes ago it was three times as many minutes past two o'clock?

Hint: How many minutes are there between 2:00 and 7:00?

Answer: 65 minutes.

There are 300 minutes between 2:00 and 7:00 and we can ignore the "40 minutes ago" for a little while and share the remaining 260 minutes in the ratio 3:1, which is 195:65.

Which means the 5 hours between 2:00 and 7:00 are made of up 195 minutes + 40 minutes + 65 minutes.

Which means it is currently 65 minutes before 7:00. So it is now 5:55 (65 minutes before 7:00).

To double check, 40 minutes ago it was 5:15 - which is 195 minutes after 2:00, as required (as 65 x 3 = 195).

Puzzle 4

Moving up or right, what is the highest total you can make, using the mathematical signs along the way?