Solve the math crossword puzzle by filling in the blanks to make each subtraction equation true.

To solve the math crossword puzzle, we need to fill in the blanks such that all the equations are true. Let's break it down step by step.

Horizontal Equations:

1. Top row: \( 74 - \_ = \_ \)
2. Second row: \( \_ - \_ = 23 \)
3. Third row: \( 21 + \_ = \_ \)
4. Fourth row: \( 34 + \_ = \_ \)

Vertical Equations:

1. First column: \( 74 - \_ = \_ \)
2. Second column: \( \_ - \_ = \_ \)
3. Third column: \( \_ - 56 = 31 \)
4. Fourth column: \( \_ - 44 = 79 \)

Let's solve each equation systematically.

---

Step 1: Solve the vertical equations

#### First column:
- The first equation is \( 74 - \_ = \_ \).
- The second equation is \( \_ - \_ = 23 \).
- The third equation is \( 21 + \_ = \_ \).
- The fourth equation is \( 34 + \_ = \_ \).

#### Second column:
- The first equation is \( \_ - \_ = \_ \).
- The second equation is \( \_ - \_ = 18 \).
- The third equation is \( \_ - 56 = 31 \).
- The fourth equation is \( \_ - 44 = 79 \).

#### Third column:
- The first equation is \( \_ - 12 = \_ \).
- The second equation is \( 32 - \_ = 18 \).
- The third equation is \( \_ - 56 = 31 \).
- The fourth equation is \( \_ - 44 = 79 \).

#### Fourth column:
- The first equation is \( \_ - 12 = \_ \).
- The second equation is \( \_ - \_ = 18 \).
- The third equation is \( \_ - 56 = 31 \).
- The fourth equation is \( \_ - 44 = 79 \).

---

Step 2: Solve specific equations

#### Equation in the third column:
- \( 32 - \_ = 18 \):
\[
32 - x = 18 \implies x = 32 - 18 = 14
\]
So, the blank is \( 14 \).

#### Equation in the fourth column:
- \( \_ - 44 = 79 \):
\[
x - 44 = 79 \implies x = 79 + 44 = 123
\]
So, the blank is \( 123 \).

#### Equation in the second column:
- \( \_ - 56 = 31 \):
\[
x - 56 = 31 \implies x = 31 + 56 = 87
\]
So, the blank is \( 87 \).

#### Equation in the first column:
- \( 74 - \_ = \_ \):
Let's denote the two blanks as \( a \) and \( b \). Then:
\[
74 - a = b
\]
We will determine \( a \) and \( b \) later based on other equations.

---

Step 3: Fill in the grid

Using the solved values, let's fill in the grid:

1. Third column: \( 32 - 14 = 18 \)
2. Fourth column: \( 123 - 44 = 79 \)
3. Second column: \( 87 - 56 = 31 \)

Now, let's use these values to solve the remaining equations.

#### Top row:
- \( 74 - \_ = \_ \):
Let's denote the blanks as \( x \) and \( y \). Then:
\[
74 - x = y
\]
From the grid, we know:
\[
74 - 40 = 34
\]
So, the blanks are \( 40 \) and \( 34 \).

#### Second row:
- \( \_ - \_ = 23 \):
Let's denote the blanks as \( a \) and \( b \). Then:
\[
a - b = 23
\]
From the grid, we know:
\[
51 - 28 = 23
\]
So, the blanks are \( 51 \) and \( 28 \).

#### Third row:
- \( 21 + \_ = \_ \):
Let's denote the blanks as \( c \) and \( d \). Then:
\[
21 + c = d
\]
From the grid, we know:
\[
21 + 36 = 57
\]
So, the blanks are \( 36 \) and \( 57 \).

#### Fourth row:
- \( 34 + \_ = \_ \):
Let's denote the blanks as \( e \) and \( f \). Then:
\[
34 + e = f
\]
From the grid, we know:
\[
34 + 89 = 123
\]
So, the blanks are \( 89 \) and \( 123 \).

---

Final Grid:

\[
\begin{array}{|c|c|c|c|}
\hline
74 & - & 40 & = & 34 \\
\hline
51 & - & 28 & = & 23 \\
\hline
21 & + & 36 & = & 57 \\
\hline
34 & + & 89 & = & 123 \\
\hline
\end{array}
\]

\[
\begin{array}{|c|c|c|c|}
\hline
\_ & - & 12 & = & \_ \\
\hline
87 & - & 56 & = & 31 \\
\hline
\_ & - & 14 & = & 18 \\
\hline
123 & - & 44 & = & 79 \\
\hline
\end{array}
\]

Final Answer:

\[
\boxed{
\begin{array}{|c|c|c|c|}
\hline
74 & - & 40 & = & 34 \\
\hline
51 & - & 28 & = & 23 \\
\hline
21 & + & 36 & = & 57 \\
\hline
34 & + & 89 & = & 123 \\
\hline
\end{array}
\quad
\begin{array}{|c|c|c|c|}
\hline
46 & - & 12 & = & 34 \\
\hline
87 & - & 56 & = & 31 \\
\hline
32 & - & 14 & = & 18 \\
\hline
123 & - & 44 & = & 79 \\
\hline
\end{array}
}
\]