Question 68852
The key to this one is that it is linear. You can then use a
formula for the slope of a straight line
As the price goes up, you sell less cups
$2/cup --- 120 cups
$3/cup --- 60 cups
Let c = number of cups sold
Let p = price per cup
c will take the place of y
and p will take the place of x in the formula
{{{(y - y[1]) / (x - x[1]) = (y[2] - y[1]) / (x[2] - x[1])}}}
{{{(c - 120) / (p - 2) = (60 - 120) / (3 - 2)}}}
{{{(c - 120) / (p - 2) = (-60) / 1}}}
{{{c - 120 = -60p + 120}}}
{{{c = (-60)p + 240}}} answer
check it
p = 3
{{{c = (-60)*3 + 240}}}
{{{c = 60}}}
OK
p = 2
{{{c = (-60)*2 + 240}}}
{{{c = 120}}}
Note that if you sell for $4/cup, you won't sell any cups