SOLUTION: a rectangular picture 12cm by 10cm has a white border of uniform width. if the area of the border is 168sq.cm, how wide is the border? one hundred tiles of a certain size are ne

Question 626022: a rectangular picture 12cm by 10cm has a white border of uniform width. if the area of the border is 168sq.cm, how wide is the border?
one hundred tiles of a certain size are needed to pave a floor. if a tile, which measures 4cm less on each side, will be used, 225 tiles will be needed. find the sizr of the larger tile.
Answer by Emsley(35) (Show Source): You can put this solution on YOUR website!
Let width of border=x So area of picture +border=120+168=288
But length=12+2x and width=10+2x
So (12+2x)*(10+2x)=288
120+44x+4x^2=288
4x^2+44x-168=0
x^2+11x-42=0
(x+14)(x-3)=0 x=3 (cant be -14
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