Question 294158
Perimeter = 2w + 2l 

l = 2w -1 <br>
substitute <i>2w - 1</i> for "l"
2w + 2(2w-1) = 28 
2w + 4w - 2 = 28<br>
combine like terms:
6w - 2 = 28 <br>
add 2 to each side:
{{{ 6w - cross(2 +2) = cross(28 +2) = 30 }}} <br>
Divide both sides by 6:
{{{ 6w/6 = 30/6 }}}
w = 5 <br>
l = 2w - 1 so 
l = 9 
and bob's your uncle!