Solve for the variable

For this problem your going to want to do the equation backwards 100-4=96 then you want to divide 96 by -12 we already know that the variable is going to be a negative because two negatives equal a positive so if it’s easier for you to divide by taking off the negative sign you can go ahead and do so but 96/-12=-8 (please mark brainliest)

The answer is biodiversity resulting from new ancestors.