Question 1070052
That should be "perimeter" of the rectangle.


{{{a+b+a+b=100}}}
{{{2a+2b=100}}}
{{{a+b=50}}}


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{{{(a-5)(b+6)}}}, this area is reduced by 60 cm-squared.
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{{{ab-(a-5)(b+6)=60}}}
{{{(50-b)b-(50-b-5)(b+6)=60}}}, substituted for a;
{{{50b-b^2-(45-b)(b+6)=60}}}
{{{50b-b^2-(45b-b^2+45*6-6b)=60}}}
{{{50b-b^2-45b+b^2-45*6+6b=60}}}
{{{50b-45b+6b-b^2+b^2-270=60}}}
{{{11b-270=60}}}
{{{11b=60+270}}}
{{{11b=330}}}
{{{b=(33*10)/11}}}
{{{highlight(b=30)}}}


Finding a:
{{{a+b=50}}}
{{{a=50-b}}}
{{{a=50-30}}}
{{{highlight(a=20)}}}