1. The problem is to divide 90 by 9. 2. The division formula is $\frac{a}{b} = c$, where $a$ is the dividend, $b$ is the divisor, and $c$ is the quotient. 3. Here, $a=90$ and $b=9$. 4. Perform the division: $$\frac{90}{9} = 10$$ 5. So, 90 divided by 9 equals 10.