<PRE><B>Question 805594</B>
Jackie mows a strip of uniform width around her 25 m by 15 m rectangular lawn and leaves a patch of lawn that is 60% of the original area. 
What is the width of the strip?
:
Let x = the width of the strip
:
Find the total area: 25*15 = 375 sq/m
then .6(375) = 225 sq/m is the remaining 60%
:
A uniform strip x, around the lawn, subtracts 2x from the original dimensions
(25-2x)*(15-2x) = 225
FOIL
375 - 50x - 30x + 4x^2 = 225
Combine like terms to form a quadratic equation
4x^2 - 80x + 375 - 225 = 0
4x^2 - 80x + 150 = 0
simplify, divide by 2
2x^2 - 40x + 75 = 0
unfortunately this will not factor, using the quadratic formula
 {{{x = (40 +- sqrt(-40^2-4*2*75 ))/(2*2) }}}
I got two solutions, approx:
x = 17.9
and
x = 2.1m is the reasonable value for x</PRE>