not sure if right sub forum, but a word problem it is. it's a bit tricky for me and would like some expertise. thanks

a friend of mine stole some clothes and wants a clean consiounce by repaying the store. she donated all the clothes. some of the clothes were 1-of-a-kind meaning that if a shirt was $60, the store lost $60 because the shirt is no longer on the rack and someone might have bought that exact shirt instead of spending money at a different store. for the non-1-of-a-kind clothes, she figures she only owes the store 1/3 (about how much the store paid the manufacturer for the shirt) of the retail price. suppose she stole $150 in 1-of-a-kind clothes and $150 of clothes that had many of the same color/size still in the store, without over/under paying back, what's the right amount to pay back the store and how should she go about paying the store? should she buy more clothes and leave/sneak them back onto the rack or donate them or what?! thanks