answer:
Let x be the normal time it takes for her to commute. We know that if she was 30min late, this would had 30 min to the journey. She takes a different route, she can travel four times faster than the normal route.
Therefore the normal time of commute will be 4 times less:
This equation states that the commute time will be four times faster and adding the 30min that she is late.
Alli <3