Coffee worth Tk. 180 per kg and Tk. 210 per kg are mixed with a third variety in the ratio 2 : 1 : 3. If the mixture is worth Tk. 225 per kg, the price of the third variety per kg will be:

Question: Coffee worth Tk. 180 per kg and Tk. 210 per kg are mixed with a third variety in the ratio 2 : 1 : 3. If the mixture is worth Tk. 225 per kg, the price of the third variety per kg will be:

Solution:
Let price of third variety be x Tk. per kg
180 × 2y + 210y + x × 3y = 225(2y + y + 3y)
⇒ 360y + 210y + 3xy = 225 × 6y
⇒ 360 + 210 + 3x = 1350
⇒ 570 + 3x = 1350
⇒ 3x = 780
∴ x = 260 Tk.