Mary, Amy, and Kim babysit. Last week, Kim earned 7.50 dollars more than Mary, and Amy earned twice as much as Kim. If Mary earned 12.80 dollars, how much did Amy and Kim earn

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.