A space research company wants to sell its two products A and B. If the product A is sold at 20% loss and the product B at 30% gain, the company will not lose anything. If the product A is sold at 15% loss and the product B at 15% gain, the company will lose Rs. 6 million in the deal. What is the cost of product B ?

Let the cost of product A be Rs. x and B be Rs. y
According to first sell
    0.80x + 1.3y = x + y
⇒ 0.2x = 0.3y
⇒ x = $$\frac{3\text{y}}{2}$$ . . . . . . (i)
According to second sell
    0.85x + 1.15y = (x + y) - 6
⇒ 0.15y = 0.15x - 6 (Multiply by 100)
⇒ 15y = 15x - 600 (Putting the value of x)
⇒ 15y = 15 × $$\frac{3\text{y}}{2}$$ - 600
⇒ 15y = $$\frac{45\text{y}}{2}$$ - 600 (Multiply by 2 both side)
⇒ 30y = 45y - 1200
⇒ 15y = 1200
⇒ y = 80 million