Let length of train A = $$l$$ metres and speed of train A = $$x$$ m/s Using, $$time = frac{distance}{speed}$$ => $$frac{l}{x} = 18$$ => $$x = frac{l}{18}$$ Length of platform = $$157.5$$ metres => $$frac{157.5 + l}{x} = 39$$ Substituting value of $$x$$, we get : => $$frac{157.5 + l}{39} = frac{l}{18}$$ => $$13l = 6l + 945$$ => $$13l - 6l = 7l = 945$$ => $$l = frac{945}{7} = 135$$ metres $$ herefore$$ Length of train B = $$(frac{135}{2}) + (157.5 imes 2)$$ = $$67.5 + 315 = 382.5$$ metres