Boys' weights

This task is about interpreting a line graph.
This graph shows the weight of Michael and his brother Patrick while they were at college.
 
Weight of Michael and Patrick while at college

Age in years

   Michael       Patrick

  
a)		   
How old was Michael when he weighed 73 kg? __________

 
b)

 
How heavy was Patrick at 18 years old? __________ kg

 
c)

 
Draw a circle around the part of the graph that shows when Michael's weight stayed about the same.

 
d)

 
The lines on the graph are moving further apart. What does this tell you?