Question 1170798

The perimeter of a rectangular fields is 200m. If the length were reduced 20m and the width reduced by 25%, the perimeter would be reduced by 30%. The original length of the field is:
<pre>Let original length, be L
        Then {{{matrix(3,3, 2L + 2W, "=", 200/2, L + W, "=", 100, W, "=", 100  -  L)}}}
We then get: {{{matrix(5,3, 2(L  -  20) + 2(.75 * (100  -  L)), "=", .7(200), 2L  -  40 + 2(75 - .75L), "=", 140, 2L  -  40 + 150 - 1.5L, "=", 140, 2L - 1.5L, "=", 140 - 110, .5L, "=", 30)}}}
Original length, or {{{highlight_green(matrix(1,6, L, "=", 30/.5, "=", 60, m))}}}