$$Two blocks with masses $0\mathrm{.}494$ kg $($A$)$ and $0\mathrm{.}728$ kg $($B$)$ sit on a frictionless surface. Between them is a spring with spring constant $28\mathrm{.}8$ N$/$m$,$ which is not attached to either block The two blocks are pushed together, compressing the spring by $0\mathrm{.}302$ meter, after which the system is released from rest. What is the final speed of the block A$?($Hint: you will need to use both conservation of energy and conservation of momentum to solve this problem$).$