A fruit seller sells only dragonfruits and chikoos. The ratio of dragonfruits to chikoos is 4 : 5. A total of 340 fruits are added. The number of dragonfruits becomes 4 times as many as before and the number of chikoos becomes 2 times as many as before. How many fruits are there at first?

	Comparing dragonfruits at first and in the end	Dragonfruits	Chikoos	Comparing chikoos at first and in the end
Before	1x4 = 4 u	4 u	5 u	1x5 = 5 u
Change		+ 340
After	4x4 = 16 u	16 u	10 u	2x5 = 10 u

The number of chikoos at first is repeated.  Make the number of chikoos at first the same.  LCM of 1 and 5 is 5.

The number of dragonfruits at first is repeated. Make the number of dragonfruits at first the same. LCM of 1 and 4 is 4.

Number of fruits at first
= 4 u + 5 u
= 9 u

Number of fruits in the end
= 16 u + 10 u
= 26 u

Number of fruits added
= 26 u - 9 u 
= 17 u

17 u = 340

1 u = 340 ÷ 17 = 20

Number of fruits at first
= 9 u
= 9 x 20
= 180

Answer(s): 180