Which algebraic symbol best represents the word "product" when translating a verbal phrase into an algebraic expression?

Which phrase from the following sentence signals that you should introduce a variable to represent an unknown quantity? Sentence: "The number of apples a student picks."

Translate the phrase into an algebraic expression using the strategy of mapping keywords to operations: "three times the sum of y and four."

Translate and solve the contextual sentence: "Twice the sum of a number and five equals the number plus twenty."

Translate the sentence and solve the resulting quadratic: "The product of a number and the difference of seven and that number is ten."