Answer:
[tex]y=\frac{3}{20}x+1[/tex]
Step-by-step explanation:
The question is
Find out the linear equation between the cost in dollar and the number of donuts holes
Let
x -----> the number of donuts holes
y ----> the cost in dollars
we have the ordered pairs
(20,4) and (40,7)
Find the slope m
The formula to calculate the slope between two points is equal to
[tex]m=\frac{y2-y1}{x2-x1}[/tex]
substitute the values
[tex]m=\frac{7-4}{40-20}[/tex]
[tex]m=\frac{3}{20}[/tex]
Find the equation of the line in point slope form
y-y1=m(x-x1)
we have
[tex]m=\frac{3}{20}[/tex]
[tex]point\ (20,4)[/tex]
substitute
[tex]y-4=\frac{3}{20}(x-20)[/tex]
Find the equation of the line in slope intercept form
[tex]y=mx+b[/tex]
Isolate the variable y
[tex]y-4=\frac{3}{20}x-3[/tex]
[tex]y=\frac{3}{20}x-3+4[/tex]
[tex]y=\frac{3}{20}x+1[/tex]
