Question 1077258
Times for each worker to do 1 job, x and y.


{{{1/x+1/y=1/12}}}


Times t and v for each worker to do half a job
{{{t+v=25}}}
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{{{system(t/x=1/2,v/y=1/2)}}}

{{{system(t=x/2,v=y/2)}}}
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{{{x/2+y/2=25}}}


{{{x+y=50}}}


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system to solve:
{{{system(1/x+1/y=1/12,x+y=50)}}}
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{{{(y+x)/xy=1/12}}}

{{{50/(xy)=1/12}}}

{{{xy/50=12}}}

{{{xy=12*50}}}

{{{xy=600}}}

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{{{x(50-x)=600}}}
{{{-x^2+50x=600}}}
{{{x^2-50x=-600}}}
{{{x^2-50x+600=0}}}

{{{x=(50+- sqrt(2500-4*600))/2}}}

{{{x=(50+- sqrt(100))/2}}}

{{{x=(50+- 10)/2}}}


{{{system(x=20,or,x=30)}}}


Times for each worker alone are  20 days and 30 days.