Tammy is mailing packages. Each small package costs her $2.10 to send. Each large package costs her $3.10 How much will it cost her to send 1 small package and 6 large packages?
To send 1 small package, it will cost her $2.10.
To send 6 large packages, it will cost her 6 * $3.10 = $<<6*3.1=18.6>>18.6
In total, it will cost her $2.10 + $18.6 = $<<2.10+18.6=20.70>>20.70 to send 1 small package and 6 large packages. Answer: \boxed{20.70}.