Part of the process:
From 8AM, less important than "whole journey took 11 and 1/4 hours", which included the 1/2 hour break. Total TRAVEL TIME was hours.
Part A, i and ii, and focusing on time quantities, not time points
Let b be the distance traveled by bus.
SPEED TIME DISTANCE
TRAIN 50 (700-b)/50 700-b
BUS 75 b/75 b
Total 10.75 700
Most of the work can now be done in one variable.
and you can solve the equation...