A fruit seller sells only dragonfruits and pomegranates. The ratio of dragonfruits to pomegranates is 1 : 2. A total of 60 fruits are added. The number of dragonfruits becomes 2 times as many as before and the number of pomegranates becomes 2 times as many as before. How many fruits are there at first?

	Comparing dragonfruits at first and in the end	Dragonfruits	Pomegranates	Comparing pomegranates at first and in the end
Before	1x1 = 1 u	1 u	2 u	1x2 = 2 u
Change		+ 60
After	2x1 = 2 u	2 u	4 u	2x2 = 4 u

The number of pomegranates at first is repeated.  Make the number of pomegranates at first the same.  LCM of 1 and 2 is 2.

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

Number of fruits at first
= 1 u + 2 u
= 3 u

Number of fruits in the end
= 2 u + 4 u
= 6 u

Number of fruits added
= 6 u - 3 u 
= 3 u

3 u = 60

1 u = 60 ÷ 3 = 20

Number of fruits at first
= 3 u
= 3 x 20
= 60

Answer(s): 60