Question 1144987
{{{y=mx+b}}}
-
y, cost for a month
x, minutes used
m, cost change per minutes used change; the per minute rate
b, flat fee


Two points described are  (210, 59) and (700, 108).
The cost per minute is {{{m=(108-59)/(700-210)}}};
{{{m=0.100}}}{{{dollars/minute}}}