Total number of boxes of matchsticks = 3600
Total number of cartons = 10
Let the number of packets in one carton be x.
⇒ Number of packets in 10 cartons = 10x.
Number of boxes of matchstick in a packet = 30
⇒ Number of boxes of matchstick in 10x packets = 30(10x) = 300x
So, we have:
Total number of boxes = Number of boxes of matchstick in 10x packets
⇒ 300x = 3600
⇒ x = 12

