When you see 'is' that means an = sign
When you see 'of' that means a x (multiplication) sign
So
30 is 60% of what number
Let us define this 'what number' as x.
So:
30 is 60% of x
Translating that into an equation based on what I said above, we get:
[tex]\sf{30 = \frac{60}{100}\times x}[/tex]
Solve for x:
[tex]\sf{\frac{30\times100}{60}=x[/tex]
And simplfying that:
[tex]\sf{x=50}[/tex]
So your final answer is [tex]\sf{\boxed{50}}[/tex]