Did anyone learn ratio and proportions, a is to b as c is to d, written in the form "a:b::c:d" ?

If I recall we would have been taught this in elementary school. We used to say: “a is to b as c is to d.
A sample problem would be “The shadow of a 3 ft yardstick is 2 ft. The shadow of a flagpole is 20 ft. How tall is the flagpole?” We’d say 2 is to 3 as 20 is to x. We’d write: 2:3::20:x
Then we’d multiply the 2 inner numbers, 3×20, to get 60 and divide by the first number, 2, to get the answer 30ft.
I do not recall ever seeing the colons or double colons anywhere else. Did you learn it that way?