May I know how to solve it? urgent....Thank you

Question

An investor remarks to a stock broker that all her stock holdings are in three companies, Eastern Airlines, Hilton Hotels, and McDonald's, and that 2days ago the value of her stocks went down $350 but yesterday the value increased by $600. the broker recalls that 2 days ago the price of Eastern Airlines stock dropped by $1 a share, Hilton Hotels dropped $1.50, but the price of McDonald's stock rose by $0.50. the broker also remember that yesterday the price of Eastern Airlines stock rose $1.50, there was a further drop of $0.50 a share in Hilton Hotels stock, and McDonald's stock rose $1. Show that the broker does not have enough information to calculate the number of shares the investor owns of each company's stock, but that when the investor or says that she owns 200 shares of McDonald's stock, the Broker can calculate the number of shares of Eastern Airlines and Hilton Hotels.

Answer 1

Let E, H, and M represent the number of shares of each stock the investor owns.

Two days ago: -1*E - 1.50*H + 0.50*M = -350.

Yesterday: 1.50*E - 0.50*H + 1*M = 600

Since you have three variables, but only two equations, you cannot solve this (you can only eliminate one variable).

However, once you know that M=200, then you can plug that in to both equations, and solve using elimination.