Christina, who is single, purchased $340$ shares of Apple Incorporated $($Nasdaq: AAPL$)$ stock several years ago for $$17,000.$ During her year$-$end tax planning, she decided to sell $170$ shares of Apple for $$7,650$ on December $30.$ However, two weeks later, Apple introduced its latest iPhone, and she decided that she should buy the $170$ shares $($cost of $$7,990)$ of Apple back before prices skyrocket.

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a$.$ What is Christina's deductible loss on the sale of $170$ shares? What is her basis in the $170$ new shares?