Question 1112768
{{{1/x+1/(x-2)=1/20}}}

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{{{20(x-2)+20x=x(x-2)}}}
{{{20x-40+20x=x^2-2x}}}
{{{40x-40=x^2-2x}}}
{{{x^2-42x+40=0}}}
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{{{x=(42+- sqrt(42^2-4*40))/2}}}
{{{x=(42+- sqrt(1604))/2}}}
{{{x=(42+- 2*sqrt(401))/2}}}
{{{x=21+- sqrt(401)}}}
{{{nearst}}}{{{whole}}}{{{hour}}},{{{x=41}}}


Faster worker:  39 hours
Slower worker: 41 hours


check:
{{{1/41+1/39}}}

{{{0.02439+0.02564}}}

{{{0.05003=1/20}}}{{{approx}}}