Answer:
55
Explanation:
Given the expression:

First, introduce parentheses as follows:
![=13+[(23+12)+7]](https://img.qammunity.org/2023/formulas/mathematics/college/mv2yfwj82rf54a3pv59qh7xbd7mhs3kg0o.png)
Apply the commutative property of addition: 23+12 = 12+23
![=13+[(12+23)+7]](https://img.qammunity.org/2023/formulas/mathematics/college/e0ece3sqaacd5ghmyae41cssuq60rwaqv9.png)
Next, apply the associative property of addition: (12+23)+7=12+(23+7).
![\begin{gathered} =13+[12+(23+7)] \\ =13+[12+30] \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/o5hq66wtdw97wxxd5ihdlhc8s4epzqrlz4.png)
We can then simplify further:

By the commutative property of addition: 13+42=42+13

The value of the given expression is 55.