Present the information on a histogram. 16. Find the inverse of the matrix and solve the simultaneous equations.

The given equations are:  
$2x + y = 21$  
$3x + 2y = 34$  
This can be written as:
$$
\begin{bmatrix} 2 & 1 \\ 3 & 2 \end{bmatrix} \begin{bmatrix} x \\ y \end{bmatrix} = \begin{bmatrix} 21 \\ 34 \end{bmatrix}
$$
Let $A = \begin{bmatrix} 2 & 1 \\ 3 & 2 \end{bmatrix}$, $X = \begin{bmatrix} x \\ y \end{bmatrix}$, and $B = \begin{bmatrix} 21 \\ 34 \end{bmatrix}$.

For a matrix $\begin{bmatrix} a & b \\ c & d \end{bmatrix}$, the determinant is $ad - bc$.
$$
\det(A) = (2)(2) - (1)(3) = 4 - 3 = 1
$$

The inverse $A^{-1}$ is given by $\frac{1}{\det(A)} \begin{bmatrix} d & -b \\ -c & a \end{bmatrix}$.
$$
A^{-1} = \frac{1}{1} \begin{bmatrix} 2 & -1 \\ -3 & 2 \end{bmatrix} = \begin{bmatrix} 2 & -1 \\ -3 & 2 \end{bmatrix}
$$
The inverse of the matrix is $\boxed{\begin{bmatrix} 2 & -1 \\ -3 & 2 \end{bmatrix}}$.

$$
\begin{bmatrix} x \\ y \end{bmatrix} = \begin{bmatrix} 2 & -1 \\ -3 & 2 \end{bmatrix} \begin{bmatrix} 21 \\ 34 \end{bmatrix}
$$
Perform the matrix multiplication:
$$
x = (2)(21) + (-1)(34) = 42 - 34 = 8
$$
$$
y = (-3)(21) + (2)(34) = -63 + 68 = 5
$$

The solution to the simultaneous equations is $x = \boxed{8}$ and $y = \boxed{5}$.