The map shown is scale of 1: 50 000 1) measure and state in centimeters the distance on the map from l to m2) calculate the actual distance in kilometers from l to m3) the actual distance two points is 4.5 km calculate the number of centimeters that should be used to represent the distance one the map

See the attached figure to better understand the problem

Part 1) 
using  a graph tool
the distance on the map from M to L  along a straight line is 5.8 cms

part 2) Calculate the actual distance in kilometers from L to M

we know that
the scale is 1:50 000
that means
1 cm on the map is in the actual-----> 50000 cm-----> 500 m-----> 0.5 km
so
if 1 cm on the map is--------> 0.5 km in the actual
 5.8 cm on the map is-------> X km
x=5.8*0.5-----> x=2.9 km

the answer Part 2) is
the actual distance in kilometers from L to M is 2.9 km

Part 3) The actual distance two points is 4.5 km calculate the number of centimeters that should be used to represent the distance one the map

if 1 cm on the map is--------> 0.5 km in the actual
 X cm--------------------------->  4.5 km
x=4.5/0.5-----> x=9 cm

the answer Part 3) is 9 cm