Question 1202541
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n = number of guests


1 guest eats 3/7 of a pound of chocolate.
n guests eat (3/7)n pounds of chocolate.


(3/7)n = 9
3n = 7*9
3n = 63
n = 63/3
n = 21


Answer: 21 guests can be served.


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Another approach:


Draw 9 rectangles to represent the 9 pounds of chocolate.
Split each rectangle into 7 equal smaller pieces. There will be 7*9 = 63 smaller pieces.
Each small piece represents 1/7 of a pound of chocolate.


Each guest eats 3/7 of a pound. It means each person eats 3 smaller blocks, so 63/3 = 21 guests can be served.
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