Question 27994
Width = x
Length = {{{2x/3+4}}}


Formula:
{{{(2x/3+4)(x)=90}}}
{{{2x^2/3+4x=90}}}
Remove fraction by multiplfing the equation by 3
{{{2x^2+12x-270=0}}}
{{{x^2+6x-135=0}}}


a=1, b = 6 c=-135
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} 
{{{x=(-6+-sqrt(6^2-4*1*-135))/(2*1)}}}
{{{x=(-6+-sqrt(36+540))/(2)}}}
{{{x=(-6+-sqrt(576))/(2)}}}
{{{x=(-6-24)/2}}} or {{{x=(-6+24)/2}}}
remove the negative
x=9


{{{2(9)/3 + 4}}} = 10


Hence, the width is 9cm and the length is 10 cm.
Paul.