On a trip, the fare was 50¢ for each adult and 25¢ for each child. If 30 passengers paid $12.25, how many adults and children went?

Which of the following equations could not be used to solve the problem?

50(30 - x) + 25 x = 1225
25 x + 50 x = 30(1225)
50 x + 25(30 - x) = 1225

the answer is  

a.

4,624π mm2

step-by-step explanation:

ending amount = beginning amount / (2^n)

where "n" = number of half-lives (or elapsed time / half-life)

ending amount = 50 mg / (2 ^10 / 5.3)

ending amount = 50 mg / (2 ^ 1.8867924528)

ending amount = 50 m / 3.6981210597

ending amount = 13.5203794557 mg

or about 13.5 mg remain

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