First convert 3.87L to ml. There are 1000ml in 1 L. We need L on the top left and bottom right so they cancel
3.87L 1000ml
--------- x -----------
1 1L
Liters cancel and we can multiply to get:
3870ml in the 1 gal container.
We need to know how many 210ml servings are in the 1 gal container so we divie 3870ml by 210ml
3870ml/210ml servings= 18.428 servings
Round to the nearest whole number. Since the tenths place is below 5 we round down to:
18 servings