Linear equations system solutions
We know that
Travel agents percentage:
y = - 2x + 30
Internet percentage:
y = 6x + 41
In order to estimate when both were used equally, we find x when y (travel agents percentage and internet percentage) is the same in both equations:
Then
y = - 2x + 30
y = 6x + 41
↓
-2x + 30 = 6x + 41
↓
30 = 6x + 41 +2x
↓
30 - 41 = 6x + 2x
↓
-11 = 8x
↓
-11/8 = x
Then x = -11/8 ≅ - 1.4
Since x = 0 corresponds to 2000 then from -1 to 0 would correspond to 1999 and from -2 to -1 would correspond to 1998
Answer: 1998