Calculate the perimeter of shape A.

Shape A is a square with a side length of 12 cm.
The formula for the perimeter of a square is $P = 4 \times \text{side}$.

$$P_A = 4 \times 12\, \text{cm}$$ $$P_A = 48\, \text{cm}$$

Shape B is a rectangle with a length of 7 cm and a width of 5 cm.
The formula for the perimeter of a rectangle is $P = 2 \times (\text{length} + \text{width})$.

$$P_B = 2 \times (7\, \text{cm} + 5\, \text{cm})$$ $$P_B = 2 \times (12\, \text{cm})$$ $$P_B = 24\, \text{cm}$$

The perimeter of shape A is $\boxed{\text{48 cm}}$.
The perimeter of shape B is $\boxed{\text{24 cm}}$.