Answer:
The latest time Sue's family can start their tour but still make it home for dinner would be:
3:00 p.m
Explanation:
Starting at 7:30pm because that's when they have dinner:
45min. + 1hr & 15mins = 2hours
2hours + 2hours & 30mins= 4hours & 30mins
Starting at 7:30 take away 4hrs 30mins:
7:30p.m - 4hrs = 3:30p.m
3:30 - 30 minutes = 3:00p.m
In conclusion, they must start their tour at 3:00 p.m to be able to reach dinner by 7:30 p.m (which is the latest time).
Have a great rest of your day
#TheWizzer