D = 200 + 200 = 400 m
S = 80 * 5/18 = 200/9
T = 400 * 9/200 = 18 sec
How long does a lorry 200 m long traveling at 80 kmph takes to cross a bridge of 200 m in length?
(1) 15
(2) 17
(3) 15
(4) 16
(5) 18