The Wu family wishes to have both their car and their RV with them during their weekend camping trip. Mrs. Wu leaves home in the RV 1.5 hours before Mr. Wu departs from home in the car. Mr. Wu drives 15 miles per hour faster than Mrs. Wu and arrives at the campsite 30 minutes later than she arrives. If Mrs. Wu drives 45 mi/h, how many miles is it from their home to the campsite?