I hope that you have found the Abacus textbook images easier to use today. The answers are below.
The problem of the day answers are:
1) 24.5 and the arrow would be drawn on the fourth line in from the 24.
2) There are 24 red counters at the start, one way to solve it is to write out the ratio alongside each other until you find the two numbers with a difference of 36 eg.
2 : 5
4 : 10
6 : 15
8 : 20 and so on
3) No he is wrong because he doubled the number rather then dividing it.
Enjoy the rest of your day!