## College Algebra 7th Edition

We know that the perimeter is 2*length+2*width. The perimeter of the poster is: Poster perimeter=$2*(140+2x)+2*(100+2x)$ The perimeter of the printed area is: Printed area perimeter: $2*140+2*100$ We know that the poster perimeter is 1.5 times the printed area perimeter: $2*(140+2x)+2*(100+2x)=1.5*(2*140+2*100)$ We solve for $x$: $280+4x+200+4x=1.5*(280+200)$ $480+8x=1.5*480$ $8x=0.5*480=240$ $x=240/8=30$ So the blank strip is 30 cm wide.