Please solve ques no-9

Dear Student

For resulting cuboid
l = 15 + 15 = 30 cm
b = 15 cm
h = 15 cm

Surface area of resulting cuboid 
= 2 (lb + bh + hl) = 2(30 x 15 + 15 x 15 + 15 x 30) 
= 2 (450 + 225 + 450) = 2 (1125) = 2250 cm²

Regards