Question 149044
Let x=amount of time it will it take all 3 of them working together to mix the 20 drinks.  {Our final equation will be of the form: Rate at which they mix drinks when working together (drinks/min) times x minutes equals 20 drinks}

Steven mixes at the rate of 4 drinks per minute
Sue mixes at the rate of 2 drinks per minute
Jack mixes at the rate of 20/15 or 4/3=1 1/3 drinks per minute

Together, they mix at the rate of 4 + 2 + (1 1/3)=7 1/3 drinks per minute

So, our equation to solve is:

(7 1/3)*x=20  divide each side by 7 1/3
x=2.73 minutes---------------------amount of time it will it take all 3 of them working together to mix the 20 drinks
CK
2.73*7.33=20
20.019~~~~20



Hope this helps---ptaylor