Answer:
a.) 
b.) 
c.) $
Step-by-step 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 <em>h</em> be the unknown number of hours:

Solve for h. Divide both sides by 7:

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 <em>h</em> be hours:

Sylvia can work less than or equal to 15 hours per week.
c.) If Sylvia can work 15 hours, plug in this value for <em>h</em> into an equation when she earns $7 per hour. Let the product of the hours and money equal <em>t</em> for total:

The most money Sylvia can earn in a week is $105.
<em>Finito.</em>
To find the answer to this, you have multiply both expressions by each other. To do this, you have to multiply each term in the first expression by each term in the second expressions. This yields the following: 3x^4-9x^3-3x^2+5x^3-15x^2-5x+10x^2-30x-10. Combing like terms and simplifying gives the final expression: 3x^4 - 4x^3 - 8x^2 - 35x - 10
This is false.
9/12 in it's lowest terms is 3/7.