(A)Total area around the house= l*b
  lenght=5m  breadth=6m
total area=30m²

Dimensions of door and 3 windows=(2*1)+(2*1.5)+(2*1.5)+(1*1.5)
Area to be painted=(total area)-(area od 1 door and three windows)
Money for 1 m²=0.5 Rs
money for 20.5 m²=20.5m²*0.5

10.area of the sheet=15*20cm²=300cm²
  area used for making the box=4(4*3)+2(3*3)
hence area of sheet wasted =300cm²-66cm²

hope the answer helped....comment below if doubt persists

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