Question 172146
lets call the width x and the length y=x+25 of the poster......the cardboard area minus the poster area would give us the area of the border(which is 1350).

the cardboard area would be (x+5)(x+25+5)=(x+5)(x+30)={{{x^2+35x+150}}}

the area of the poster is x(x+25)={{{x^2+25x}}}
:
so {{{x^2+35x+150-x^2-25x=1350}}}={{{10x=1200}}}
:
{{{highlight(x=120)}}}cm in width
:
{{{highlight(y=120+25=145)}}}cm in length