Question 53920
PROBLEM ONLY MAKES SENSE IF THE YOU KNOW THE TOTAL NUMBER OF COINS THERE ARE!  

IF THERE ARE 24 COINS THAN THE THICKNESS OF EACH COIN IS 1 INCH.

TOTAL HEIGHT OF THE TWO STACKS ARE 15+9=24 INCHES AND THERE ARE 24 COINS THEN 

24/24=1 INCH EACH.