Substitution would be the best method for solving which system? Group of answer choices y = 2x x + y = 28 x + y = 7 x - 4y = 12 3x - 2y = 18 4x + 5y = 60 5/3x = 6y 2x - 3y = 8

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.