Fahim and Robin invested in a business where the investment of Robin is double of Fahim. But Fahim immediately invested 15000 Tk. that brings him double the profit of Robin after one year. Robin's investment was -

Question: Fahim and Robin invested in a business where the investment of Robin is double of Fahim. But Fahim immediately invested 15000 Tk. that brings him double the profit of Robin after one year. Robin's investment was -

Solution:
Let initially the investment of Fahim is = X
So, the investment of Robin is = 2X

ATQ,
(X + 15000) : 2X = 2 : 1
⇒ 4X = X + 15000
⇒ 3X = 15000
∴ X = 5000 Tk.

Hence, the initial investment of Robin is = (2 × 5000) = Tk. 10000