Question 275481
THE FORMULA IS:
1/9+1/6=1/X FIND A COMMON DENOMINATOR & ADD THE LEFT SIDE.
(6+9)/9*6=1/X ADD THE NUMERATOR & MULTIPLY THE DENOMINATOR.
15/54=1/X CROSS MULTIPLY.
15X=54 DIVIDE BY 15.
X=54/15
X=3.6 HOURS TO FILL THE BLIMP WORKING TOGETHER. 
PROOF:
1/9+1/6=1/3.6
(6+9)/9*6=1/3.6
15/54=1/3.6
54=15*3.6
54=54