91Ó°ÊÓ

An investor will invest a total of \(\$ 15,000\) in two accounts, one paying \(4 \%\) annual simple interest and the other \(3 \%\). If he wants to earn \(\$ 550\) annual interest, how much should he invest at each rate?

Find the midpoint of each segment with the given endpoints. (-10,4) and (7,1)

Solve each system. $$ \begin{aligned} -4 x+3 y-z &=4 \\ -5 x-3 y+z &=-4 \\ -2 x-3 z &=12 \end{aligned} $$

Solve each system by graphing. If the system is inconsistent or the equations are dependent, say so. \(x+y=-5\) \(y-x=-5\)

Solve each system by the substitution method. Check each solution. $$ \begin{array}{l} \frac{1}{2} x+\frac{1}{3} y=-\frac{1}{3} \\ \frac{1}{2} x+2 y=-7 \end{array} $$

Pure acid is to be added to a \(10 \%\) acid solution to obtain \(54 \mathrm{~L}\) of a \(20 \%\) acid solution. What amounts of each should be used? (Hint: Pure acid is \(100 \%\) acid.)

A one-cup serving of orange juice contains \(3 \mathrm{mg}\) less than four times the amount of vitamin \(\mathrm{C}\) as a one-cup serving of pineapple juice. Servings of the two juices contain a total of \(122 \mathrm{mg}\) of vitamin \(\mathrm{C}\). How many milligrams of vitamin \(\mathrm{C}\) are in a serving of each type of juice? (Data from U.S. Agriculture Department.)

Find the midpoint of each segment with the given endpoints. (-9,3) and (9,8)

Solve each system by graphing. If the system is inconsistent or the equations are dependent, say so. \(x-2 y=6\) \(x+2 y=2\)

Solve each system by the elimination method. Check each solution. $$ \begin{array}{l} 5 x+4 y=12 \\ 3 x+5 y=15 \end{array} $$