here v indicates the final velocity of the ball
so we have
iniitial velocity along the incline - vcos45=v/√2
intitial velocity erpendicular to it - vsin45=v/√2
further acceleration in direction of intitial velocity along incline= g/√2
and perpendicular to it= -g/√2
so let the ball return to the incline after time "t"
we have
v/√2 - g/√2t=-v/√2
√2v=gt/√2
t=2v/g
so let range =s
s=v/√2t+1/2(g/√2)t2
we already know t