need help asap

150 = 10 times log x/10⁻¹²

I will assume that you mean

150 = 10 times log[ x/10⁻¹²]

$150=10\times log(\frac{x}{10^{-12}})\\ 150=10\times log(x*10^{12})\\ 150=10\times[ log(x)+log(10^{12})]\\ 150=10\times[ log(x)+12log(10)]\\ 15=log(x)+12*1\\ 3=log(x)\\ 10^3=10^{log(x)}\\ 10^{log(x)}=10^3\\ x=1000$

or maybe you mean:

$150 = 10 \times \frac{log (x)   }{   10^{-12}}\\ 15 = \frac{log (x)   }{   10^{-12}}\\ 15\times 10^{12} = log (x)  \\ x=10^{15\times 10^{12} }\\ x=10^{1.5\times 10^{13} }\\~\\ \text{WOW that is a big number !}$