28.  A man is aged 71 and his daughter is 34. (a) What age will the daughter be when she is half the age of her father? (b) What age was the man when he was three times the age of his daughter? 
29.  Here is a magic square using the numbers 1 to 16 (with no repeats) arranged so the magic total of the numbers along every row, column and diagonal is 34. It is possible, by replacing ONLY ONE of the numbers and then rearranging all of them, to make the magic total 36. To do that  which number must be replaced by what? 

30.  Both the sails of my boat are in the shape of a rightangled triangle. They are of different areas, each being an exact number of square metres. All their edge lengths are different as well, but each is an exact number of metres. However, they do have one property in common. The area of each is numerically equal to its perimeter. What is the area of each sail? 
The winner of Competition #9 was Linda Phillips of Sutton Coldfield
The answers were:
25.  35 triangles 
26.  Kit, Phil, Alexis, Terri 
27.  50/(4 + pi) or 7.00 sq.metres (to 3 sig. figs.) 