:
x

when i tried it, i got up until canceling the 5s and getting x - 1 - x - 2 = 21

what did i do wrong?

6 on both sides and twelve on the top and the bottom

step-by-step explanation:

the mistake in the pattern is that :

b. the decimal point was moved one too many place values each time

the correct pattern could be made by :

b. moving the decimal point to the right the same numbers of place values as the exponents