Do 2:3 and 6:12 form a proportion

No

Step-by-step explanation:

In order to get from 2 to 6, you would need to multiply 2 x 3. To get from 3 to 12, you would need to multiply 3 x 4. In order for two ratios to form a proportion, you have to be able to get from one to the other by multiplying the numerator and the denominator by the same number.

See, when you multiply the numerator and denominator by the same number, you're technically multiplying it by 1. 2/2 simplifies to 1, 3/3 simplifies to 1, and so on. If you multiply the numerator and denominator by different numbers, you're no longer multiplying it by 1. 3/4 doesn't simplify to 1, for example.