Petrolyn motor oil is a combination of natural oil and synthetic oil. It contains 4 liters of natural oil for every 7 liters of synthetic oil. If 399 liters of synthetic oil are used, how many liters of Petrolyn oil will be made?

Question

anonymous · Answer

@Hero, can you please help me again?

anonymous · Answer

I mean 57*4= x             x+399=answer

hero · Answer

The ratio of natural oil to synethic oil is 

$$\frac{4}{7}$$

$$\frac{4}{7} = \frac{x}{399}$$ Solve that to find how much natural oil there is. 

Then 399 + x = the amount of Petrolyn oil used.