The total perimiter of a rectangle is 30 inches. If the lenght is three times the width, what is the length?

Question

This question has to do with math. It's an equations that testes your ability to write equations. 

Answer 1

Let w represents the width.  We know the the length L = 3w.   The formula for the sum of the sides would be L+w+L+w=P or 2L+ 2w = P.   Replacing L with its formulaic value of 3w then 2(3w)+2w = P and simplifying the formula 8w=P.  Now we also know that the perimeter P=30.  So we know that 8w=30.   Solving the formula w= 3.75.  And since L=3w.  L=3(3.75)=11.25

Answer 2

The unknowns are the rectangles length say ,L, and width say ,w. The perimeter 2*L + 2*w is 30, and the length is three times the width. Realizing these as equations,

2*w + 2*L = 30

3*w -     L  = 0 

These can be solved for w and L as w=3.75, L=11.25. Giving the desired rectangle.