Number of miles Leeann rode on Day 1 =6.75 miles
Number of miles Leeann rode on Day 2=12.4 miles
The question is asking us to find the total number of miles she rode in all.
Number of miles Leeann rode on Day 1 and day 2 = 6.75+12.4=19.15 miles.
Number of miles she ride her bike both days is 19.5 miles.