Fill in the blanks to make the equation true.
15a^4 - 5a^4 b - ___ + 20a^2 = 12a^2 b - 8b^4 - 4^b + ___
4a^2 b^2 12ab^2 18a^2 5a^2 b^3 16b^2
The answer is 18a^2, 5a^2 b^3.
+1313 
