I’m performing some exercises in order to get the optimal price of some product such a potato chips, biscuits, drinks, etc. But I’ve found that some of them have positive elasticities. This can makes sense for me, as if some biscuits brand is not so successful (in sales), price can decrease in order to be more attractive. But under this scenario, how can I establish an optimal price? I’m using a log-log model to obtain elasticities. Also, at this scenario can I take into account cross-elasticities? By example, how can biscuits influence (cannibalise) chips’ sales?