Respuesta :

erliandb
slope formula
points (1,40) and (4,85)
    m=[tex] \frac{y_{2}- y_{1} }{x_{2}-x_{1}} [/tex]
    m=[tex] \frac{85-40}{4-1} [/tex]
    m=[tex] \frac{45}{3}[/tex]


 y=mx+b
y=40; x=1; m= 45/3

       40=(45/3) + b
       40 - (45/3)= b
       b= 25

therefore

y=(45/3)x + 25
when x=0
y=25

so the value of the book was $25

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