Respuesta :
Answer
a. s = -19.95 + 1.29d
b. slope = 1.29. It represents the cost of 1 non-reusable bottle of water
c. s-intercept = -19.95. It represents the cost of a reusable bottle of water
d. At the end of six weeks, he will save $18.75
e. He will break even after 16 days of school
Step-by-step explanation
a.
Variables
• d: number of school days after buying the reusable bottle
,• s: the amount of money saved
Carlos buys 1 bottle per day. Each bottle costs $1.29. Then, after d days would spend 1.29d dollars.
On the other hand, the cost of a reusable stainless steel bottle is $19.95.
If he buys the reusable bottle and avoids the cost of each non-reusable bottle of water, his savings will be:
[tex]\begin{gathered} \text{ savings }=\text{ - reusable bottle cost + cost avoided } \\ s=-19.95+1.29d \end{gathered}[/tex]b. The slope of the line is the coefficient of the d-term, that is,
[tex]slope=1.29[/tex]It represents the cost of 1 non-reusable bottle of water
c. The s-intercept is the constant term in the equation, that is,
[tex]\text{ s-intercept =}-19.95[/tex]It represents the cost of a reusable bottle of water
d. Assuming that Carlos doesn't go to school at the weekends, then there are 6x5 = 30 days after 6 weeks. Substituting d = 30 into the equation:
[tex]\begin{gathered} s=-19.95+1.29\cdot30 \\ s=-19.95+38.7 \\ s=18.75\text{ \$} \end{gathered}[/tex]At the end of six weeks, he will save $18.75
e. If Carlos break even, his savings will be zero. Substituting s = 0 into the equation and solving for d:
[tex]\begin{gathered} 0=-19.95+1.29d \\ 0+19.95=-19.95+1.29d+19.95 \\ 19.95=1.29d \\ \frac{19.95}{1.29}=\frac{1.29d}{1.29} \\ 16\approx d\text{ \lparen we need to round up because there are no decimal number of days\rparen} \end{gathered}[/tex]He will break even after 16 days of school