Question 124437
L=W+5
(W+5)W=70
W^2+5W-70=0
USING THE QUADRATIC EQUATION {{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} 
W=(-5+-SQRT[5^2-4*1*-70])/2*1
W=(-5+-SQRT[25+280])/2
W=(-5+-SQRT305)/2
W=(-5+-17.46)/2
W=(-5+17.46)/2
W=12.46/2
W=6.23 ANSWER FOR THE WIDTH.
L=6.23+5=11.23 FOR THE LENGTH.
PROOF
6.23*11.23=70
70~70