Answer :
a function is for every input, you get 1 output
so sale items purchased to cost
if bought 1 then paid c (original cost)
if bought 2 then paid c ( buy 1 get one)
so it is a functinon because it is only not a function if
bought x and pay y or z, can only be 1
so it is a functnion
so sale items purchased to cost
if bought 1 then paid c (original cost)
if bought 2 then paid c ( buy 1 get one)
so it is a functinon because it is only not a function if
bought x and pay y or z, can only be 1
so it is a functnion