The proportion is new value : old value = 4 : 3 , as I said, which means x/3300 = 4/3. solve that. You appear to be solving 3300/x = 4/3.
Your addition suggests that you are interpreting the "increase" to be by adding 4/3 (like a percent increase), rather than the new value itself being 4/3 of the original. Can you offer evidence that it is to be taken that way (such as an example like this in your textbook)?