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Erin bought christmas cards for $2 each to send to her family and friends. which variable is the dependent variable?

This is a rational expression because the denominator contains a variable. this is a polynomial with 3 terms. this is a rational expression because the denominator contains a variable. this is a polynomial with 4 terms. this is a rational expression because the denominator contains a variable. this is a polynomial with 4 terms. this is a rational expression because the denominator contains a variable. this is a polynomial with 3 terms. this is a rational expression because the denominator contains a variable. this is a polynomial with 5 terms.

Erik buys 2.5 pounds of cashews. if each pound of cashews costs $7.70, how much will he pay for the cashews?