One canned juice drink is 30 percent orange juice, another is 10 percent orange juice. how many liters of each should be mixed together in order to get 20l, that is 12 perfect orange juice

Let there be x litters of 30 percent juice and (20-x) litters of 10 percent juice.

0.30x+0.10(20-x)=20*0.12
0.3x+2-0.1x=2.4
0.2x=0.4
x=2
20-x=20-2=18

mix 2 litters of 30 percent juice and 18 litters of 10 percent juice.