 Quandaries and Queries My question is Mr.Carter is very cautious. He decides to invest in only three stocks: one low stock, one high stock, one medium stock. Given that the expected annual yields are 6% for low stock, 7% for medium stock, and 8% for high stock, he wants his investment in medium stock to be half of his total investment in low and high stock. How much should I invest in each type fo stocks to expect a total annual return fo \$650 form my investments? I was wondering if the set up is: x+y+z=10,000 .06x+.07y+.08z=? How do you get the rest? Hi Bob, I assume from the first line of your setup that the total investment is \$10,000 and that the amounts invested in the low, medium and high yield stocks are \$x, \$y and \$z respectively. I agree with your first equation x + y + z = 10,000 Your second equation claculates the expected amount of interest for a year and you are told this is \$650. Thus 0.06x + 0.07y + 0.08z = 650 You have three variables, x, y and z so you probably need another equation. Rerreading the problem I see "he wants his investment in medium stock to be half of his total investment in low and high stock". That is he wants y to be half of x + z. Thus the third equation is y = (x + z)/2 I would now substitute this expression for y into the first two equations, simplify and then solve the resulting two equations for x and z. I'll substitute into the second equation for you and then you can do it with the first equation. Since y = (x + z)/2, the second equation 0.06x + 0.07y + 0.08z = 650 becomes 0.06x + 0.07 (x + z)/2 + 0.08z = 650 I would now multiply both sides by 2 and simplify 0.12x + 0.07 (x + z) + 0.16z = 1300 0.12x + 0.07x + 0.07z + 0.16z = 1300 0.19x + 0.23z = 1300 Harley Go to Math Central