Required Area will be `A` = Area of base + Area of both side faces + Area of back face
`A = lb+2bh+hl`
where l is length, b is breadth and h is height.
Here, `l = 80 cm, b = 30cm, h = 40cm`
So, `A = (80**30+2**30**40+80**40)cm^2`
`A = 2400+2400+3200 = 8000cm^2`