Answer:
4 days
Explanation:
You use basic inverse variation for this problem. you can also use rtd tables
t=3 days and d=1 (because the job is one job not many).
tP=12 days d=1
tQ=x D=1
so your rate would be 1/3; 1/12; and 1/x respectively.
and since the 3 days is when p and q can do it together,
1/3=1/p+1/q
So the way to do this is:
1/3=1/12+1/x
Solve to get x=4
So it would take 4 days for Q to do it alone.
Check: 1/3=1/12+1/4;
1/3=1/3
correct.