of means multiplication
is means equal
lets say this blank is a
so:
30% x a = 60
30% = 30/100 = 3/10
So:
3/10 x a = 60
Multiply by 10/3 on both sides to isolate a
a = 60 x 10/3
Simplify that:
a = 20 x 10
a = 200
So your final answer is [tex]\boxed{\bf{200}}[/tex]