Solution:
The given graph shows Giselles total cost for buying CDs using a discount card,
From the graph,
we can see that the y-intercept is 20.
Also the straight line is passing through the point (1,30) and (5,80).
So the slope of the line can be given as
[tex] m=\frac{80-30}{5-1}=\frac{50}{4}=12.5\\
\\
\text{As we know the equation of line in slope intercept form is given by }\\
\\
\
y=mx+b\\
\\
m=slope, b=y-intercept\\
\\
\text{Hence equation of the line will be }\\
\\
y=12.5x+20 [/tex]
Hence option [D]
