Question 745680
{{{X[1]=1.60}}}
{{{Y[1]=6}}}
{{{X[2]=13}}}
{{{Y[2]=3.00}}}

{{{m=(Y[2]-Y[1])/(X[2]-X[1])=(3.00-1.60)/(13-6)=1.4/7=0.2)}}}


so using the first pair (6,1.6)


we'll write:


Y-1.6=0.2(X-6)


so a 25 minute call will cost...

{{{Y=1.60+.2(25-6)=1.60+.2*19=5.4}}}

$5.40