2 pumps in parallel (both pump at same time) take 6 daes, so rate=1/6
1 pump at a time...1 pump take x daes, other take x+9
time tu fill... (1/x) +[1/(x+9)] =1/6
or (6/x) +[6/(x+9)] -1=0
6*(x+9) +6*x -x*(x+9)=0
-x^2 -9x +6x+6x +54=0
-x^2 +3x +54=0
or +x^2 -3x-54=0
quadratik equashun giv zeroes=9 or -6
tri x=9, then other rate=18
(1/9) +(1/18)=3/18=1/6