Question 777800
120 liters of fuel, containing 3% oil, is available for a certain 2-cycle engine. this fuel is used for another engine requiring 10% oil mixture. how many liters of oil must be added?
***
let x=amount of oil must be added
..
3%(120)+100%x=10%(120+x)
3.6+x=12+.10x
.90x=8.4
x=28/3 
amount of oil must be added=28/3 liters