Question 1023118
x and x-3;
{{{A=x(x-3)}}}


x+1 and x-3+1;
x+1 and x-2;
{{{B=(x+1)(x-2)}}}


{{{B-A=18}}}
{{{(x+1)(x-2)-x(x-3)=18}}}
{{{x^2+x-2x-2-x^2+3x=18}}}
{{{x-2x+3x=18}}}
{{{2x=18}}}
{{{highlight_green(x=9)}}}


Find the sides, now knowing x.