Explanation:
this question just means :
for what x do we get f(x) = -96.6
when we look into the table, then we find
f(x) = -96.6 for x = 4
there is only one x-value (at least in the table you gave us here) with that y-value of -96.6.
remember
f(x) = y = functional expression in x or
direct table association with x.