Answer:
C. 468 mm²
Step-by-step explanation:
Surface area of the composite solid = 2(LW + LH + WH)
Length (L) = 12 mm
Width (W) = 6 mm
Height (H) = 2 + 7 = 9 mm
Plug in the values into the formula
Surface area = 2(12*6 + 12*9 + 6*9)
Surface area = 2(72 + 108 + 54)
Surface area = 2(234)
= 468 mm²
