let speed of the train be v mph, & length of the train be L mi,

2 min = 1/30 h & 10 sec = 1/6 min = 1/360 h, so

L = (65 - v) /30 ....... [ I ]

L = (65 + v) / 360 ... [ II ]

(65+v)/(65-v) = 360/30 = 12

65+v = 780 - 12v

13v = 715

v = 55 mph

L = (65 - 55) 30 = 1/3 mi

= 5280/3 ft

= 1760 ft

ans: 1760 ft