Question 904047
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Hi,
     *[illustration rectangle.png].
A = Lw
(6x-17)w = 28cm^2
6x^2 - 17w - 28 = 0
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
{{{x = (17 +- sqrt( 961 ))/(12) }}}
{{{x = (17 +- 31)/(12) }}} (Tossing out the negative solution for unit measure)
{{{ x = 48/12}}} = 4cm, the width.  L is 7cm.  {{{6*4-17}}}