SOLUTION: : 1 jar contains 5/6 alcohol and another 8/9 alcohol . how many liters taken from each jar are required to fill a third jar with capacity of 24 liter so that the mixture will be se

The other tutor used 1 unknown.  Here it is using 2. Word problems involving
multiply answers are usually easier to set up if you use multiple unknowns.

Let the answer be

We take x liters out of the first jar and y liters out of the second jar,
so that x + y = 24 liters.

The amount of alcohol in the x liters is x [and the rest water].

The amount of alcohol in the y liters is y [and the rest water].

So the amount of alcohol in the third jar is x + y [and the
rest water].

The third jar contains 24 liters.

So also the amount of alcohol in the third jar is ·24 or 21 liters of
alcohol [and the rest water].

So we set the two expressions for the amount of alcohol in the third jar
equal, and we have

               x + y  = 21

So our system of equations is

               x + y  = 21
                          x + y = 24

Clear the first of fractions by multiplying it through by LCD of 18

               15x + 16y = 21
                   x + y = 24

Solve that system and get x = 6 and y = 18

Answer: Take 6 liters from the jar that contains ths alcohol and 
18 liters from the jar that contains ths alcohol.

Edwin