Question

Can anybody help me regarding 1st question

Answer 1

100 Km is the actual distance 
then it descended 11/10 km = 1.1 km
means 100 - 1.1 = 98.9 is the distance when it descended 11/10 km
then it ascended 3/5 km
we will add 3/5 (0.6) to 98.9 = 98.9 + 0.6 = 99.5 is the distance after it ascended 3/5 km 
then again it descended 9/10 (0.9) = 99.5 - 0.9 = 98.6 is the distance when it again descended 9/10. 
The current distance is 98.6 km.