This ought to be a P6 question. Nevertheless, if pupils can look at this question as a proportion question, it is still solvable by P5.
5/12 of journey --> 1.5 h or 3/2 h
Whole journey --> 12/5 x 3/2 h = 36/10 h = 3.6 h or 3 h 36 min
(a) 1/2 of the journey --> (3h 36min) / 2 = 1 h 48 min
For the 2nd part, use a time line. Plot it back words from 12.52pm:
. __48min_ _____ 1h _______
. / \ / \
|----------|------------------|
11.04am 11.52am 12.52pm
(b) He started the journey at 11.04 am.
