A train traveling with constant speed crosses a 90m long platform in 12 seconds and a 120m long platform in 15 seconds.Find the length of the train and its speed.  Choose one:	A) 30	B) 40	C) 60	D) 50	E) NOne
Let the length of the train be x m and its speed be y m/sec.   Then, x/y = 12 =&gt; y = x/12   (x + 90)/12 = x+120/15 =&gt; x = 30 m.   30nswer:30
<result>A</result>
A train traveling with constant speed crosses a 90m long platform in 12 seconds and a 120m long platform in 15 seconds.Find the length of the train and its speed.