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
