<PRE><B>Question 1194365</B>
&lt;br&gt;
The cost goes up by $200-$120 = $80 when the number of people goes up by 25-15 = 10; the slope is 80/10 = 8.  So the equation is of the form&lt;br&gt;
y = 8x+b&lt;br&gt;
Use either given data point to find b:&lt;br&gt;
120 = 8(15)+b
120 = 120+b
b = 0&lt;br&gt;
ANSWER: y = 8x&lt;br&gt;
The slope of 8 means the cost goes up by $8 for each additional person.&lt;br&gt;
The cost for a party for 40 people is 40($8) = $320.&lt;br&gt;
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