is means equal sign
percent means over hundred
of means multiplication
lets say this number we are talking about is 'n'
[tex]12 = \frac{60}{100} \times n \\12=0.6n \\n =20[/tex]
Plug back in n=20 into the equation to make sure it works.
[tex]12 = \frac{60}{100} \times 20 \\12 = \frac{60}{5}\\12=12[/tex]
So n = 20 is your answer