[latex]25\% \ of \ x= 12 \\\\ \frac{25}{100}*x=12 \\\\ \frac{1}{4}=\frac{12}{x} \\\\ x=\frac{4*12}{1} \\\\ \boxed{x=48}[/latex]

If we know that 12 is 25% of x (unknown) And we want to find x we can just multiply 12 by 4, because 12 is 25%: so 12 = [latex] \frac{25}{100} [/latex] 12 = [latex] \frac{1}{4} [/latex] / *4 48 = 1 - 1 means 100% of x, so just x The result is 48