Final answer:
If two thirds of the costumes were polychromatic and there were 4800 polychromatic costumes, the total number of costumes can be found by solving the equation 2/3 * x = 4800 and isolating x. The number of costumes that were not polychromatic can then be found by subtracting the number of polychromatic costumes from the total.
Step-by-step explanation:
If two thirds of the costumes were polychromatic and there were 4800 polychromatic costumes, we can find the total number of costumes. Let x be the total number of costumes. We can set up the equation:
2/3 * x = 4800
To solve for x, we need to isolate it. We can do this by multiplying both sides of the equation by the reciprocal of 2/3, which is 3/2. Simplifying, we get:
x = 4800 * (3/2) = 7200
So there were 7200 costumes in total. To find the number of costumes that were not polychromatic, we subtract the number of polychromatic costumes from the total:
7200 - 4800 = 2400
Therefore, there were 2400 costumes that were not polychromatic.