Optical Supply Company

1.) Optical Supply Company offers credit terms of 2/10, net 60. If Optical Supply is considering a change in its credit terms to one of those indicated, explain whether the change should increase or decrease sales.
(a) 2/10, net 30,
(b) net 60,
(c) 3/15, net 60,
(d) 2/10, net 30, 30 extra.

2). Why are interest rates on short-term loans not necessarily comparable to each other? Give three possible reasons.