is means equal
of means multiplication
Soooo
[tex]\sf{18 = \frac{60}{100} \times x}[/tex]
And simplifying that
[tex]\sf{18 \times \frac{100}{60} = x}[/tex]
And simplifying that more:
[tex]\sf{30 =x}[/tex]
So x=30
So the number you are looking for is 30