Question 1182705
To avoid the use of ounces or fluid ounces,


{{{10(drops/minute)*60(minutes/hour)*24(hours/day)*365(days/year)*(1/20)(mL/drops)*(1/3785.4)(gallons/mL)}}}


You should look at the units carefully and finish computing.


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Read again what your question is asking.  Given was how many drops per minute.  WANTED was how many  GALLONS PER YEAR.  To begin solving, start with "ten drops per minute", write this value with the units, and then begin placing the necessary conversion factors with their units, until the desired units are accounted.   NOTICE that as arranged, most of the units will cancel and what stays is the gallons per year.  What is still then to do, is the computation of the numbers.


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The work would be something this way or like it:


{{{10(drops/minute)*60(minutes/hour)*24(hours/day)*365(days/year)*(1/20)(mL/drops)*(1/3785.4)(gallons/mL)}}}


{{{((10*60*24*365)/(20*3785.4))(drops/minute)(minutes/hour)(hours/day)(days/year)(mL/drops)(gallons/mL)}}}


{{{((10*3*24*365)/3785.4)(drops/cross(minute))(cross(minutes)/cross(hour))(cross(hours)/cross(day))(cross(days)/year)(mL/drops)(gallons/mL)}}}


{{{((10*3*24*365)/3785.4)((drops*mL*gallons)/(year*drops*mL))}}}


{{{((720*365)/3785.4)(gallons/year)}}}
and you can finish the computation.