Question 1057167
Hi there,
Total matches in one box = 40
Mr John used 24 matches 
Fraction = 24/40  cancelled down = 3/5
Total number of matches in a dozen boxes
= 12 x 40 = 480 matches
Mr John used 24 matches 
Fraction = 24/480  cancelled down = 1/20.
Answers
a) 3/5
b) 1/20
Hope this helps :-)