Answer:
84
Step-by-step explanation:
To get from 4 to 12, you multiply with 3.
Everything is 3 times as big in the larger rectangle.
This includes the perimeter.
Example:
small rect 4x10, perimeter 4+4+10+10 = 28
large rect 12x30, perimeter 12+12+30+30 = 84
but also 28x3 = 84