Answer
.9153 meters per second
Work Step by Step
We use conservation of momentum to find the velocity of each one following the collision:
$350=950\Delta v_s\\ \Delta v_s=.3684 \ m/s $
And:
$350=640\Delta v_b\\ \Delta v_b=.5469 \ m/s $
Since they are moving apart, we add these values to find:
$\Delta v = .5469+.3684=\fbox{.9153 meters per second}$
