3/4 = 0.75 or 75%. So you need to find 75% of 200... Simply multiply 0.75 or 3/4 by 200 and you will get your answer... (0.75)(200) = 150....
You could also realize with this problem that 3/4 of 200 is 150 because 50 goes into 200 4 times. 50 = 1/4, 100 = 2/4 = 1/2, 150 = 3/4 & 200 = 4/4 = 1.