91Ó°ÊÓ

Solve each system of equations by addition-subtraction, or by substitution. Check some by graphing. $$\begin{aligned} &2 x-3 y=5\\\ &3 x+3 y=10 \end{aligned}$$

Solve each systems of equations by any method. \(1.21 x+1.48 y+1.63 z=6.83\) \(4.94 x+4.27 y+3.63 z=21.7\) \(2.88 x+4.15 y-2.79 z=2.76\)

Unknowns in the Denominator $$\begin{aligned} &\frac{8}{x}+\frac{6}{y}=3\\\ &\frac{6}{x}+\frac{15}{y}=4 \end{aligned}$$

Unknowns in the Denominator $$\begin{aligned} &\frac{1}{x}+\frac{3}{y}=11\\\ &\frac{5}{x}+\frac{4}{y}=22 \end{aligned}$$

Solve each systems of equations by any method. \(5 a+b-4 c=-5\) \(3 a-5 b-6 c=-20\) \(a-3 b+8 c=-27\)

Solve each system of equations by addition-subtraction, or by substitution. Check some by graphing. $$\begin{aligned} &3 x-2 y=-15\\\ &5 x+6 y=3 \end{aligned}$$

Solve each systems of equations by any method. \(p+3 q-r=10\) \(5 p-2 q+2 r=6\) \(3 p+2 q+r=13\)

Applications Involving Mixtures. A distributor has two gasohol blends: one that contains \(5.00 \%\) alcohol and another with \(11.0 \%\) alcohol. How many gallons of each must be mixed to make 500 gal of gasohol containing \(9.50 \%\) alcohol?

Unknowns in the Denominator $$\begin{aligned} &\frac{5}{x}+\frac{6}{y}=7\\\ &\frac{7}{x}+\frac{9}{y}=10 \end{aligned}$$

Solve each system of equations by addition-subtraction, or by substitution. Check some by graphing. $$\begin{aligned} &7 x+6 y=20\\\ &2 x+5 y=9 \end{aligned}$$