Cassidy drove 13.6 miles from school to pick up her brother at home. Then she drove him to a doctor's appointment. If she drove a total of 21.4 miles, which equation gives the number of miles she drove from home to the doctor's appointment?
1.) 13.6 - m = 21.4
2.) 21.5 + 13.6 = m
3.) m - 21.4 + 21.4
4.) 13.6 + m = 21.4