Explanation:
I guess "logg" is a typo.
otherwise we would have 2 variables in one equation (log to the base of g of x), for which there would be infinitely many solutions.
so, I assume it is actually
log(x) = -2
that is short for
log10(x) = -2
even though many programming libraries on computers actually mean ln(x) when providing the function log(x).
so, log(x) means actually log10(x) is my second assumption.
and then
log10(x) = -2
gets solved by putting everything to the power of the logarithm base :
x = 10^-2 = 1/10² = 1/100 = 0.01
if another base has to be used, then 10 has to be replaced by that other base. the principle always stays the same.