Respuesta :
[tex]\bf y = \stackrel{\stackrel{monthly~fee}{\downarrow} }{10}~~\stackrel{\stackrel{month}{\downarrow }}{x}+\underset{y-intercept}{\stackrel{\stackrel{registration~fee}{\downarrow }}{30}}~\hfill \impliedby \begin{array}{|c|ll} \cline{1-1} slope-intercept~form\\ \cline{1-1} \\ y=\underset{y-intercept}{\stackrel{slope\qquad }{\stackrel{\downarrow }{m}x+\underset{\uparrow }{b}}} \\\\ \cline{1-1} \end{array}[/tex]
Answer: a. The y-intercept is 30. This is the cost of registration.
Step-by-step explanation:
The standard equation of line in intercept form is given by  :-
[tex]y=mx+c\ \ \ \ \ \ \ (i)[/tex], where m is the slope of the line and c is the y-intercept.
Given : Sara plotted the data and determined that the average gym costs consist of a one-time registration fee and a monthly fee modeled by the equation :-
[tex]y = 10x + 30[/tex]
By comparing it to the equation (i), we have
c=30 and m=10
i.e. The y-intercept is 30.
Also, y-intercept of any function shows the starting value of the function when x=0.
Thus, This is the cost of registration ( starting fee).