The radius of a circle is 10 meters. What is the length of a 135° arc?

135/360 = 0.375 * d * pi -> 0.375 * 20 meters * 3.14 = 23.55 meters.

I'm doing this problem on an online Geometry program. 23.55 is the right answer but it willonlytake it in the form of 15pi/2 meters. Here's a screenshot: http://prntscr.com/2d8pi3

How do I arrive to that simplification from 23.55?