91Ó°ÊÓ

In Exercises \(13-18\), solve the system by the method of elimination. $$ \left\\{\begin{array}{l} 5 u+6 v=14 \\ 3 u+5 v=7 \end{array}\right. $$

In Exercises \(15-20\), solve the system by the method of substitution. $$ \left\\{\begin{array}{l} 5 x-2 y=10 \\ 3 x+2 y=6 \end{array}\right. $$

In Exercises \(7-16\), sketch the graph of the system of linear inequalities. $$ \left\\{\begin{array}{l} x-y>2 \\ x-y<-4 \end{array}\right. $$

In Exercises \(15-20\), solve the system by the method of substitution. $$ \left\\{\begin{array}{l} 3 x+7 y=2 \\ 5 x-3 y=-26 \end{array}\right. $$

In Exercises \(13-18\), solve the system by the method of elimination. $$ \left\\{\begin{array}{l} 2 x+3 y=16 \\ 5 x-10 y=30 \end{array}\right. $$

In Exercises 17-22, sketch the graph of the system of linear inequalities, and label the vertices. $$ \left\\{\begin{array}{lr} y> & -5 \\ x \leq & 2 \\ y \leq x+2 \end{array}\right. $$

You travel 16 miles upstream and 16 miles downstream on a motorboat trip. You run the motor at the same speed going up and down the river, but because of the speed of the current, the trip upstream takes 2 hours and the trip downstream take \(1 \frac{1}{3}\) hours. Determine the speed of the boat in still water.

In Exercises \(13-18\), solve the system by the method of elimination. $$ \left\\{\begin{array}{l} 3 x-4 y=1 \\ 4 x+3 y=1 \end{array}\right. $$

In Exercises 17-22, sketch the graph of the system of linear inequalities, and label the vertices. $$ \left\\{\begin{array}{lr} y \geq & -1 \\ x \leq & 5 \\ y \leq x+4 \end{array}\right. $$

In Exercises \(15-20\), solve the system by the method of substitution. $$ \left\\{\begin{array}{l} 4 x+3 y=15 \\ 2 x-5 y=1 \end{array}\right. $$