PLEASE provide a very detailed answer so it can be referenced in layman terms, thanks

Required information [The following information applies to the questions displayed below] Kubin Company's relevant range of production is 16,000 to 24.500 units. When it produces and sells 20.250 units, its average costs per unit are as follows: Required: 1. What is the incremental manufacturing cost incurred if the company increases production from 20,250 to 20,251 units? 2. What is the incremental cost incurred if the company increases production and sales from 20.250 to 20.251 units? 3. Assume that Kubin Company produced 20.250 units and expects to sell 19.980 of them, If a new customer unexpectedly emerges and expresses interest in buying the 270 extra units that have been produced by the company and that would otherwise remain unsold, what is the incremental manufacturing cost per unit incurred to sell these units to the customer? 4. Assume that Kubin Company produced 20.250 units and expects to sell 19,980 of them. If a new customer unexpectedly emerges and expresses interest in buying the 270 extra units that have been produced by the company and that would otherwise remain unsold, what incremental selling and administrative cost per unit is incurred to sell these units to the customer