A grocery shopper tosses a$($n$)8\mathrm{.}2$ kg bag of

rice into a stationary $18\mathrm{.}0$ kg grocery cart.

The bag hits the cart with a horizontal speed

of $6\mathrm{.}9$ m$/$s toward the front of the cart.

What is the final speed of the cart and bag?

Answer in units of m$/$s$.$