I found: ##396m##
We can use the relationship from kinemamatics:
##color(red)(v_f^2=v_i^2+2ad##
with:
##v_f=## final velocity which is zero at the top;
##v_i=## initial velocity (the same on Earth and on the Moon I suppose);
##a=## accelration of gravity (##=g## downwards);
##d=## distance (height in this case).
We have:
On Earth: ##0=v_i^2-2g*66##
so that ##v_i^2=2g*66##
On the Moon: ##0=v_i^2-2/6gd##
so that: ##v_i^2=2/6gd##
so considering the same values for ##v_i^2## we can write:
##2cancel(g)*66=2/6cancelgd##
##d=6*66=396m##
