Which pair of ratios form a proportion? a. 2 : 3 and 3 : 4 b. 8 : 12 and 16 : 20 c. 4 : 7 and 12 : 21 d. 9 : 15 and 10 : 16

C.
You can simplify 12:21 to 4:7 by dividing 12 by 3 to get 4 and by dividing 21 by 3 to get 7.  Because dividing both those numbers in the one ratio by 3 gives you the other ratio, they are a proportion.

$18.25 ($365 divided by 20)

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