Answer:
4200
Explanation:
On any normal table with lots of data, the y-intercept is where the x is 0. Now on this table there is no 0 in the first column so we have to look for a pattern.
It looks like you were trying to find the pattern by subtracting the numbers in each column and that was a very good idea. 3500-2100 is 1400. Matching with this in the first column is 3-1 is 2. So for every 2 on the left, we go down 1400 on the right. You can confirm this with the 3 and 5 on the left and the corresponding 2100 and 700 on the right. The calculations come out the same.
SO, in the left column you have 0 (imagine they made a line for you to fill in) in the right column the number would go up 700 more(following the pattern) Therefore, 0 would go with 4200.
So the y-intercept is 4200