Answer:
(-21a^5×b)/(2+4b)
Step by step explanation:
The question isn't complete and clear as we were not told what to determine from the expression.
Looking at the question, we can tell we are to simplify the expression.
[(-7a² × 9a³x³) :(-3ax³)] : [( 10a) -(-20a b) : (-5a²b)]
First we would work with expressions in each parenthesis (bracket).
Then we would work on the answer we derive after opening the parenthesis.
See attachment for detail