Aparticular submarine is 12 m long. a model of it was built with a scale of 1 cm: 3 m. how long is the model? show all work.

1cm : 3m

to get from 12m to 3m you have to divide by 4, so if:

3 x 4 = 12

then you do the same to the 1cm and you get:

1 x 4 = 4

Therefore:

1cm : 3m
4cm : 12cm

the model is 4cm

the answer is the above in bold
hope it helped :)
and sry if my explanation wasn't detailed enough or if i misunderstood the question