Question

Petrolyn motor oil is a combination of natural oil and synthetic oil. It contains 5 liters of natural oil for every 3 liters of synthetic oil. If 380 liters of natural oil are used, how many liters of Petrolyn oil will be made?

Answer 1

5 l of natural oil - 3 l of synthetic oil
380 l of natural oil - x l of synthetic oil

$x=\dfrac{380\cdot3}{5}=228$

$380+228=608$

608 l

Answer 2

5/3 = 380/x....5 of natural to 3 of synthetic = 380 of natural to x of synthetic
cross multiply because this is a proportion
(5)(x) = (3)(380)
5x = 1140
x = 1140/5
x = 228 <=== 228 liters of Petrolyn are used