The length of a board is thrice its breadth. If the perimeter of the board is 720 cm, find the dimensions of the board. If the cost of painting the board is rs 20 per square metre, find the cost of painting the board on one side?
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Let length=3b
Breadth=b
Perimeter =2(l+b)
720cm=2(3b+b)
720cm=2(4b)
360cm=4b
90cm=b
0.9m=b
l=3b
l=3(90)
l=270cm
l=2.7m
Area =l×b
=0.9×2.7
=2.43m^2
Cost of painting of cardboard
=20×2.43
= Rs48.6
Breadth=b
Perimeter =2(l+b)
720cm=2(3b+b)
720cm=2(4b)
360cm=4b
90cm=b
0.9m=b
l=3b
l=3(90)
l=270cm
l=2.7m
Area =l×b
=0.9×2.7
=2.43m^2
Cost of painting of cardboard
=20×2.43
= Rs48.6
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