So if there are 34% white marbles, that means that 66% are black (100% - 34% = 66%).
If 100% = 1.00, then 66% = 0.66.
Now, you just need to multiply the total by this decimal in order to find the number of black marbles:
6657 x 0.66 = 4393.62, which can be rounded to 4394
Therefore, there are about 4394 black marbles in the jar.
I hope this helps!
