(1) If you need x cartons of this specification, please use the algebraic expression of x respectively: the cost of buying cartons from carton factory is (4X) yuan.

The cost of processing and manufacturing cartons by silk company itself is (16000+2.6X) yuan.

(2) If you are the decision maker, which scheme do you think you should choose? And explain why.

When 4X≥ 16000+2.6X, X≥ 1 1428.5 is obtained.

Therefore, when you need 1 1428 cartons, you can choose to customize them. When 1 1429 cartons are needed, choose to lease production.