Problem Solving

An investment fund manager is considering three stocks, P, Q, and R for her portfolio. For the cost of 1 share of P, she could buy 3 shares of Q or 5 shares of R. If she invested an amount equal to the cost of 4,500 shares of Q but purchased equal numbers of shares of P and R and no shares of Q, how many shares of R did she buy?
250
625
1,250
3,650
3,750

The LCM of 1,3 and 5 is 15. So let's say that share P costs 15 which means share Q costs 5 and share R costs 3

Cost of 4500 shares of Q = 4500x5

She bought equal number of shares of P an R say Y

So 15Y + 3Y = 4500x5

18Y = 4500x5

Y = 250x5 = 1250

Y = 1250

Thanks.. i got it