There are two ways to attack this problem. One is to try and find out the maximum price possible per chair and see if our price per chair is under that. The other is to calculate the overall cost using our price per chair and see if that is under our budget.
Since you say x is the price of a chair, we are trying to see what is the maximum price you can pay per chair per your $2000 budget.
B = Budget (maximum cost)
T = Table
X = Maximum price per chair
B = T + 6X
2000 = 419.99 + 6X
1580.01 = 6X
X = $263.34 (rounded up to nearest penny)
Therefore, we can buy the chairs since they are less than $263.34.
The second method would be:
C = 419.99 + 6(199.99)
C = 419.99 + 1199.94
C = 1619.93
Since the Cost is less than our $2000 budget we can buy the chairs and table.