We are asked to find out whether the given expressions are equivalent or not
Part A:
![x+x+x+x\quad and\quad 4x](https://img.qammunity.org/2023/formulas/mathematics/college/q959zibod3movs7xn937lb68dkeq5ojqsg.png)
These two expressions are equivalent since the sum of four individual x is equal to 4x.
![x+x+x+x=4x](https://img.qammunity.org/2023/formulas/mathematics/college/onx0w9pnjn1mad5scddh5itcbgn8w3r7h5.png)
For example:
Substitute x = 2
![\begin{gathered} x+x+x+x\quad and\quad 4x \\ 2+2+2+2\quad and\quad 4(2) \\ 8\quad and\quad 8 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/83oe9t9mhqhis1znjmkt73c44n51smbjrm.png)
As you can see, the result of both expressions is equal therefore, these are equivalent expressions.
Part B:
![5x\quad and\quad x+5](https://img.qammunity.org/2023/formulas/mathematics/college/d5c5a4n5xbqnp6bxc6imo7u0bjfmbnh6n3.png)
These two expressions are not equivalent since, in the first expression, 5 is being multiplied with x and in the second expression 5 is being added to x.
![5x\\e x+5](https://img.qammunity.org/2023/formulas/mathematics/college/b923er76d6gww3fds10pu72ufnsbf64p9z.png)
For example:
Substitute x = 1
![\begin{gathered} 5x\quad and\quad x+5 \\ 5(1)\quad and\quad 1+5 \\ 5\quad and\quad 6 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/i38g0jgjeznyl1qeq8neac1u7epkc91dh5.png)
As you can see, the result of both expressions is not equal therefore, these are not equivalent.