Determine whether $(1,2)$ is a solution of the system:
\[
\begin{array}{r}
2 x+3 y=8 \\
x+4 y=9
\end{array}
\]
Is $(1,2)$ a solution of the system?
Yes
No

Step 1 ：Given the system of equations: \[\begin{array}{r} 2 x+3 y=8 \\ x+4 y=9 \end{array}\]

Step 2 ：We are asked to determine whether the point (1,2) is a solution to this system.

Step 3 ：To do this, we substitute x=1 and y=2 into both equations and check if both equations are satisfied.

Step 4 ：For the first equation, substituting x=1 and y=2 gives us \(2(1) + 3(2) = 8\), which is true.

Step 5 ：For the second equation, substituting x=1 and y=2 gives us \(1 + 4(2) = 9\), which is also true.

Step 6 ：Since both equations are satisfied, we can conclude that (1,2) is a solution to the system of equations.

Step 7 ：\(\boxed{\text{Yes, (1,2) is a solution of the system.}}\)