log was used calculate big numbers before calculators
log is a re-arranged way to show a number with an exponent
example
log₂ 16 = 4 means 2^4 = 16
logx(Z) = y means x^y=Z
log(x-6)/log(2) + log(x)/log(2) = 4
(log(x-6)+ log(x))/log(2) = 4
(log(x-6)+ log(x)) = 4log(2)
(log(x-6)x) = log(16)
x=8