Answer:
150 red bars
Explanation:
To solve this, you can use proportions. First, set up your two ratios (4:3 is equal to 200:___). Each ration represents the number of green bars to red bars. To get from 4 to 200, you can multiply 4 by 50. You could do the same to 3. 3 times 50 is 150, so there are 150 red bars.