What is the ratio 12:3 in its lowest form?

would you divide both by 3?

Yes, to simplify a ratio, you can divide both parts of the ratio by their greatest common divisor (GCD). In this case, you can divide both 12 and 3 by 3 to simplify the ratio 12:3.

Dividing 12 by 3 gives you 4, and dividing 3 by 3 gives you 1. Therefore, the simplified form of the ratio 12:3 is 4:1.