A triangle has numbers in its three vertices and one in the center. If the top-left is 9, the bottom is 8, and the center is 98, what is the top-right number, given the pattern (Top-left * Top-right)

The top-left number is 9.
The bottom number is 8.
The center number is 98.
Let the missing top-right number be $X$.

The pattern is: $(\text{Top-left number} \times \text{Top-right number}) + \text{Bottom number} = \text{Center number}$.
Substitute the known values into the pattern:

First, subtract 8 from both sides of the equation:

Next, divide both sides by 9:

The missing number in the top-right circle is 10.