3. The distance between Fossil Cave and Cabin C is 9 miles. So, 3/5 times 9 miles= 5.4 miles. They walked 5.4 miles.
4. The campers in Cabin D walked 1/6 of the way to Mammoth Mountain. The distance between the 2 places is 25 miles. 1/6*25 miles= is about 4.2 miles. They walked about 4.2 miles to Mammoth Mountain.