We use a rule of three to solve the problem, we say 200 is the 100% as an unknown number x is the 30%
100% ----> 200
30% ------> x
x = (30)(200)/100
x = 60
therefore, 60 is the 30% of 200
We can also calculate that number directly:
(30%)(200) = (30/100)(200) = 60