Sheila loaded 21 trucks every 28 minutes. At this rate how long will it take to load 12 trucks

[math_celebrity]

Sheila loaded 21 trucks every 28 minutes. At this rate how long will it take to load 12 trucks.

Let m be the number of minutes it takes Sheila to load 12 trucks. We set up a proportion of trucks to minutes:
21/28 = 12/m

Type this proportion into our search engine,and we get:
m = 16