Question 108745
Let x=the x-coordinate
____y=the y-coordinate


Here, I want the x-coordinate to be the no. of miles and the y-coordinate to be the price. So, the points are ({{{2}}},{{{7}}}) , ({{{9}}},{{{24.50}}})


Let's find the slope


slope={{{(y-increment)/(x-increment)}}}={{{(24.50-7)/(9-2)}}}={{{17.50/7}}}={{{2.5}}}

Now, let's use the slope-intercept form {{{y=mx+b}}}  where m=slope and b=y-intercept

m=2.5 but b is unknown. So, let's use (2,7)  for x=2 and y=7

{{{y=mx+b}}}
{{{7=2.5*2+b}}}
{{{7=5+b}}}
{{{7-5=5-5+b}}}
{{{2=0+b}}}
{{{0+b=2}}}
{{{b=2}}}

Thus, the equation is {{{y=2.5x+2}}}


Which is interpreted as "the price is calculated by multiplying the no. of miles by 2.5 and by adding 2 to the result"

Graph:

{{{graph(1000,1000,-20,20,-20,20,2.5x+2)}}}


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