Answer: 240.6cm *squared*
Step-by-step explanation:
Surface Area= (2 x Area of 1st face) + (2 x Area of 2nd face) + (2 x Area of 3rd face)
= (2 x 10.5cm x 5.4 cm) + (2 x 10.5 cm x 4.0cm) + (2 x 5.4cm x 4.0cm)
= 113.4cm*squared* + 84.0cm *squared* + 43.2cm *squared*
= 240.6cm *squared*
OR
= 2 x (sum of the 3 faces)
= 2 x (56.7cm * squared* + 42.0cm *squared* + 21.6cm *squared*)
= 2 x 120.3cm *squared*
= 240.6cm *squared*
