travel distance on first day - 1/5 (0.2)
travel distance on second day - 2/5 (0.4)
total distance traveled on two days - 1/5+2/5 (or) 0.2+0.4
1/5+2/5 (or) 0.2+0.4
[as the two denominators are same we can just add the numerators]
3/5 (or) 0.6
Therefore, the family traveled 3/5 (0.6) on two days. So the answer is C. 3/5