### Be Prepared

### Try It

ⓐ Since both equations are in standard form, using elimination will be most convenient. ⓑ Since one equation is already solved for $x$, using substitution will be most convenient.

ⓐ Since one equation is already solved for $y$, using substitution will be most convenient; ⓑ Since both equations are in standard form, using elimination will be most convenient.

Mark burned 11 calories for each minute of yoga and 7 calories for each minute of jumping jacks.

Erin burned 11 calories for each minute on the rowing machine and 5 calories for each minute of weight lifting.

The principal amount for the bank loan was $4,000. The principal amount for the federal loan was $14,000.

- ⓐ $\{\begin{array}{c}0.75d+2e\le 25\hfill \\ 360d+110e\ge 1000\hfill \end{array}$
- ⓑ

- ⓒ yes
- ⓓ no

- ⓐ $\{\begin{array}{c}140p+125j\ge 1000\hfill \\ 1.80p+1.25j\le 12\hfill \end{array}$
- ⓑ

- ⓒ yes
- ⓓ no

### Section 5.1 Exercises

Given that it is only known that the slopes of both linear equations are the same, there are either no solutions (the graphs of the equations are parallel) or infinitely many.

### Section 5.2 Exercises

### Section 5.3 Exercises

### Section 5.4 Exercises

The amount of the first year’s loan was $30,000 and the amount of the second year’s loan was $12,000.

### Section 5.5 Exercises

Julia and her husband should buy 12 pounds of City Roast Columbian coffee and 8 pounds of French Roast Columbian coffee.

### Section 5.6 Exercises

- ⓐ $\{\begin{array}{c}90b+150g\ge 500\hfill \\ 0.35b+2.50g\le 15\hfill \end{array}$
- ⓑ

- ⓒ No
- ⓓ Yes

- ⓐ $\{\begin{array}{c}7c+11p\ge 35\hfill \\ 110\text{c}+22p\le 200\hfill \end{array}$
- ⓑ

- ⓒ Yes
- ⓓ No

### Review Exercises

$\{\begin{array}{c}x+y=\mathrm{-32}\hfill \\ x=2y-2\hfill \end{array}$ The numbers are –10 and –22

$\{\begin{array}{c}j+d=7200\hfill \\ d=j+1600\hfill \end{array}$ Debbie earned $4400 and Jim earned $2800