P, Q, and R opened a shop together. P invests four times as much as Q, and Q invests one-fifth as much as R. After one year, the total profit is Tk 18,000. What is Q's share of the profit?

Question: P, Q, and R opened a shop together. P invests four times as much as Q, and Q invests one-fifth as much as R. After one year, the total profit is Tk 18,000. What is Q's share of the profit?

Solution:
Let R's investment = x taka
Then Q's investment = 1/5 of x = x/5
And P's investment = 4 × (x/5) = 4x/5

So the ratio of investments (or profit) is:
P : Q : R
= 4x/5 : x/5 : x
= 4 : 1 : 5

Total ratio = 4 + 1 + 5 = 10

Total profit = Tk 18,000

∴ Q's share = (1/10) × 18000 = Tk 1800