A fruit seller sells only pears and starfruits. The ratio of pears to starfruits is 1 : 2. A total of 42 fruits are added. The number of pears becomes 4 times as many as before and the number of starfruits becomes 3 times as many as before. How many fruits are there in the end?

	Comparing pears at first and in the end	Pears	Starfruits	Comparing starfruits at first and in the end
Before	1x1 = 1 u	1 u	2 u	1x2 = 2 u
Change		+ 42
After	4x1 = 4 u	4 u	6 u	3x2 = 6 u

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

The number of pears at first is repeated. Make the number of pears 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
= 4 u + 6 u
= 10 u

Number of fruits added
= 10 u - 3 u 
= 7 u

7 u = 42

1 u = 42 ÷ 7 = 6

Number of fruits in the end
= 10 u
= 10 x 6
= 60

Answer(s): 60