Sarah is 16 years old. she left home at age 15; her parents no longer support her. sarah entered into a contract with best groceries for the purchase of $100 of groceries on credit. the groceries consisted of basic, necessary items. however, their reasonable value is only $80. if sarah discovers that she has been overcharged and refuses to pay, best is entitled to collect:

$80                    

Explanation:

Sarah and Best Groceries entered into an agreement or contract for purchasing necessary groceries on credit of a total value of 100 dollar. But Best Groceries made a breached and overcharged Sarah because the actual value of the items costs to 80 dollar. Best overcharged 20 dollar for the groceries. Thus when Sarah finds this and refuses to pay the amount, Best can collect only the actual value of the items which is 80 dollar.

Thus the answer is -- $80