Verified answer

Answer:

lateral surface area of the room with ceiling

= 2h(l+b)+ lb

=2×3(5+4)+(5×4)

=6×9+20

=54+20

=74m^2

cost of white washing

=74 × 7.50

= ₹555

I hope this helps you

Answer:

amount of room to be painted = lateral surface area of room + area of ceiling

lateral surface area = 2(lh+bh)

=2{(5×3)+(4×3)}

=2(15+12)

=2(27)

=54m²

area of ceiling

=l×b

=5×4

=20m²

amount of room to be painted = 20 + 54

= 74m²

rate of painting 1m² room = ₹7.50

rate of painting 74m² room = 7.50 × 74

= ₹555