Answer:
[tex]\huge \frac{8}{45} [/tex]
Step-by-step explanation:
[tex] \frac{9}{10} - \frac{13}{18} \\ \\ = \frac{9 \times 9}{10 \times 9} - \frac{13 \times 5}{18 \times 5} \\ \\ = \frac{81}{90} - \frac{65}{90} \\ \\ = \frac{81 - 65}{90}\\ \\ = \frac{16}{90} \\ \\ = \frac{8}{45} \\ [/tex]