Let's define the following variable:
r = number of rabbits Miranda has.
2r = number of rabbits Ramon has (Ramon has twice as many rabbits as Miranda)
4r = number of rabbits Carla has (Carla has 4 times as many rabbits as Miranda)
If Ramon has 6 rabbits, how many rabbits does Carla have? We have the equation:
4 x (6 ÷ 2) = number of rabbits Carla has.
4 x 3 = 12
Carla has 12 rabbits.