Answer:
a.)
![hours=13](https://img.qammunity.org/2021/formulas/mathematics/high-school/h5vop522jkneatmwfveflqi7obbtxma1vk.png)
b.)
![h\leq 15](https://img.qammunity.org/2021/formulas/mathematics/high-school/otxq7fdc6djjgpa3vkoaqg5nb9x2z4855k.png)
c.) $
![$105](https://img.qammunity.org/2021/formulas/mathematics/high-school/l6hbyrjrdfib2otssxqk57dag5paqer0dq.png)
Explanation:
a.) If she earns $7 'per' hour, this multiplication. After a week, we need to see how many hours she worked to earn $91, so this goes behind the equal sign. Let h be the unknown number of hours:
![7h=91](https://img.qammunity.org/2021/formulas/mathematics/high-school/s6nse7n8cxfzbvdj9a0bdo3vlr9snh6k4h.png)
Solve for h. Divide both sides by 7:
![(7h)/(7)=(91)/(7)\\\\h=13](https://img.qammunity.org/2021/formulas/mathematics/high-school/urez3s78t3wsbr3eat6y4kk96mc78ant1e.png)
Sylvia worked 13 hours at a rate of $7 an hour.
b.) She can work at most 15 hours a week. At 'most' can also mean less than or equal to. Let h be hours:
![h\leq 15](https://img.qammunity.org/2021/formulas/mathematics/high-school/otxq7fdc6djjgpa3vkoaqg5nb9x2z4855k.png)
Sylvia can work less than or equal to 15 hours per week.
c.) If Sylvia can work 15 hours, plug in this value for h into an equation when she earns $7 per hour. Let the product of the hours and money equal t for total:
![t=7(15)\\t=105](https://img.qammunity.org/2021/formulas/mathematics/high-school/cil8wmof0ncsy63v44mfkd9nsbeminbup5.png)
The most money Sylvia can earn in a week is $105.
Finito.