9 has factors of 3*3.
2 is prime, so no factors.
from those two denominators, we can get the LCD of hmmm simply their product, namely 18.
[tex]\bf \cfrac{4}{9}+\cfrac{9}{2}\implies \stackrel{\textit{using the LCD of 18}}{\cfrac{(2)4+(9)9}{18}}\implies \cfrac{8+81}{18}\implies \cfrac{89}{18}\implies 4\frac{17}{18}[/tex]
now, recall that, to get the mixed fraction, we divide 89 ÷ 18, the quotient goes up front, the "4", and the remainder is the one atop, the "17".
