Question 634850
Let x=amount of time it takes John to do the work
Then John works at the rate of 1/x of the job per day
x+10=amount of time it takes Ganesh to do the work
Then Ganesh works at the rate of 1/(x+10) of the job per day
Together they complete the work in 12 days
So, together they work at the rate of 1/12 of the job per day
So our equation to solve is:
 1/x +1/(x+10)=1/12 multiply each term by 12x(x+10)
12(x+10)+12x=x(x+10)
12x+120+12x=x^2+10x collecting like terms, we get
x^2-14x-120=0  quadratic in standard form and it can be factored
(x-20)(x+6)=0
x=20-----------------amount of time it takes John to do the work
x+10=20+10=30 days----ANSWER-- time it takes Ganesh working alone
and 
x=-6---------------work is positive---no good

CK
1/20+1/30=1/12
3/60+2/60=1/12
5/60=1/12
1/12=1/12

Hope this helps---ptaylor