With exponents in a fraction, whenever something is negative, you put it to the other side of the fraction to make it positive (numerator to denominator or denominator to numerator).
So, put -18b^2 to the bottom to make it +18b^2.
Put -a to the top to make it +a and -3b to the top to make it +3b.
So,
2a^2+a+3b
------------------- would be
18b^2 the answer.