A shopkeeper has two varieties of lentils priced at Taka 60 per kg and Taka 80 per kg. In what ratio should he mix them to get a mixture worth Taka 68 per kg?

Question: A shopkeeper has two varieties of lentils priced at Taka 60 per kg and Taka 80 per kg. In what ratio should he mix them to get a mixture worth Taka 68 per kg?

Solution:
Cheaper variety price of lentils, p = 60 Taka
Expensive variety price of lentils, q = 80 Taka
mixture price, r = 68 Taka

Ratio = (q - r)/(r - p)
=(80 - 68)/(68 - 60)
=12/8
= 3 : 2