Answer:
scale factor = 
Step-by-step explanation:
The scale factor is the ratio of corresponding sides, image to original, that is
scale factor =
=
= 
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1 pizza costs $12.75 and feeds 4
To feed 24 students he needs 24 ÷ 4 = 6 pizzas , then
6 cost = 6 × $12.75 = $76.50