#### Answer

The length of the city park is $90$ yd and the width is $30$ yd.

#### Work Step by Step

Let $x =$ the width of the city park
$2(3x) + 2(x) = 240$
$6x + 2x = 240$
$8x = 240$
$x = \frac{240}{8}$
$x = 30$ yd
Let $y = $ the length of the city park
$y = 3x$
$y = 3(30)$
$y = 90$ yd