A fruit seller sells only passion fruits and pomegranates. The ratio of passion fruits to pomegranates is 3 : 4. A total of 156 fruits are added. The number of passion fruits becomes 4 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 passion fruits at first and in the end	Passion Fruits	Pomegranates	Comparing pomegranates at first and in the end
Before	1x3 = 3 u	3 u	4 u	1x4 = 4 u
Change		+ 156
After	4x3 = 12 u	12 u	8 u	2x4 = 8 u

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

The number of passion fruits at first is repeated. Make the number of passion fruits at first the same. LCM of 1 and 3 is 3.

Number of fruits at first
= 3 u + 4 u
= 7 u

Number of fruits in the end
= 12 u + 8 u
= 20 u

Number of fruits added
= 20 u - 7 u 
= 13 u

13 u = 156

1 u = 156 ÷ 13 = 12

Number of fruits at first
= 7 u
= 7 x 12
= 84

Answer(s): 84