math
posted by jason on .
a poster is 25cm taller than it is wide. it is mounted on a piece of cardboard so that there is a 5cm border on all sides. if the area of the border alone 1350cm^2, what are the dimensions of the poster?
It is almost a must to draw a diagram but I can't do that on the computer. It will help you to do so.
 
 
 
 
 
 
 
 
 
 
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height of inside poster = w+25
width of inside poster = w
area of inside poster =w*(w+25)
Border is 5 cm on each side; therefore, its height is w+25+top5cm+bottom 5cm=w+35
Border width = w + left 5 cm + right 5 cm = w + 10 cm.
area of entire unit is (w+35)*(w+10)
area of inside poster is w*(w+25)
The border is 1350 cm^{2}. Set this into an equation.
area entire unit1350=area inside unit.
(w+35)*(w+10)1350 = w(w+25)
Solve for w, which is the width of the inside poster. Add 25 to that to obtain the height. Then add 10 to each to obtain the dimensions of the entire frame. Post your work if you get stuck.

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