Let the length of the canal = x m
Breadth = 2 m.
Depth = 8 dcm = 0.8 m,
According to the problem,
x×2×(0.8) = 240
∴ x = \frac{240}{2 × 0.8} =\frac{240 × 10}{2 × 8} = 150 m
Total Surface Area = 2 (l x b + b x h + l x h)
= 2 (150 × 2 + 2 × 0.8 + 150 × 0.8)
= 843.2 m2