Question

A salesman travelled 2/5 of his journey before lunch and 3/8 of his journey after lunch.

Answer 1

2/5+3/8= 31/40 therefore he still has 9/40 to go.
to get this you multiply the two denominators together
5x8=40 which is your denominator
then you cross multiply the two numerators
2x8=16
3x5=15
to get the final
15/40+16/40=31/40
and you are left with 9/40