Algebraic equations word problem

Question

the length of a rectangular field is thrice it's breadth. It' perimeter is 400 meters. Find its length and breadth.

Answer 1

In this case, allow Length = 'l' and width/breadth = 'b'

The length is three times the breadth, so l=3b.

The perimeter of a rectangle is always calculated with the formula 2l + 2b = P.

Therefore, if l = 3b, then 2l + 2b =400 becomes 6b + 2b =400.

8b = 400

b=50 m

l=3b=150 m.