Question

the length breadth and height of a room are 5 m 4 m and 3 m

Answer 1

area for white washing = area of 4 walls + area of ceiling

= 2(l+b)h + lb
=2 ×9 ×3 + 20
= 54 + 20
= 74 m square

cost of white washing = 74 ×7.5
=555

Answer 2

Here is your answer.Hope its right.