Question

The length of a rectangular wooden board is thrice its width. If the width of the board is 120 cm, find the cost of framing it at the rate of $5 for 20 cm.

Answer 1

length=120×3=360
breath=120
area =l×b
=360×120
=43200cm^2
1cm=20/5
=4
43200×4
=172800

Answer 2

take width = b
then length(a) be 3 times i.e. 3b
since we have to find cost of frame therefore perimeter i.e. P = 2(a+b) = 8b
since b is 120 , 8b = 960
now 5$ for 20 cm
now fron unitary method (5×120)/20 = 30$