Conservation of energy and momentum

Blocks $A$‍ and $B$‍ are pressed together with a spring between them. When the blocks are released from rest, the spring pushes the blocks apart so the $0.35\text{kg}$‍ block $A$‍ moves up the $30\mathrm{°}$‍ ramp to the left and the $5.0\text{kg}$‍ block $B$‍ moves to the right at $v_{f_B}=0.25{\displaystyle \frac{\text{m}}{\text{s}}}$‍. Assume friction is negligible.