how do you solve 1/4x-18=1/2x-6

I will assume you mean

(1/4) x - 18 = (1/2) x - 6
then
-18 + 6 = (2/4) x - (1/4)x

-12 = x/4

x = - 48

If I misinterpreted, please repeat using parentheses to show what is numerator and what is denominator.