Question 785147

Here is another method:

Let x = litres of alcohol taken from first jar. 
Let y = litres of alcohol taken from second jar.

We will need two equations to get value of x and y.

So first equation is our quantity constraint, i.e., we just need total 24 litres.

x + y = 24

Next equation comes from final composition of alcohol.

5x/6 + 8y/9 = 7*24/8

Solving these two, you get 
x=6 
y=18

Hope it helps:)