First we have to plot two points per graph
Function 1
y=-2x+30
Points
x y
0 -2*0 + 30 = 30
10 -2*10 + 30 = 10
Points: (0,30) and (10,10)
Function 2
y=6x+41
Points: (0,41) and (1,47)
x y
0 6*0 + 41 = 41
1 6*1 + 41 = 47
Then we plot the graph
From the graph we can deduce that the year when travel agents and Internet were used equally was approximately 1999 ( one year before 2000)