Petrolyn motor oil is a combination of natural oil and synthetic oil. It contains 7 liters of natural oil for every 5 liters of synthetic oil. If 355 liters of synthetic oil are used, how many liters of petrolyn oil will be made?

What we know:

Petrolyn motor oil is a combination of natural oil and synthetic oil. It contains 7 liters of natural oil for every 5 liters of synthetic oil.

What we need to find:

If 355 liters of synthetic oil are used, how many liters of petrolyn oil will be made?

Set up a proportion to find how much natural oil is used.

7L natural oil/5L synthetic oil = x/355 synthetic oil where x=natural oil

7/5=x/355

(5) (x) = (7) (355) cross multiplied

5x=2485 simplified

5/5x=2485/5 multiplicative inverse

x=497L

Now, add both synthetic oil and natural oil to find amount of petrolyn oil.

355 L synthetic oil + 497 L natural oil = 852 L of petrolyn oil