I need help with this practice Can you solve, please explain step-by-step, *as I am new to this branch/topic of math*

Explanation
This is Algeba, an aspect of Math
We are told to find th correct optionthat satisfies the condition of a and b
Given that
a =5 and b =8
To go about this, we will simply substitute a = 5 and b=8 into each of the equation and cross-check the value with 104
Let us check for the first option
[tex]\begin{gathered} 8+a+8+b \\ 8+5+8+8=29 \\ since\text{ 29 is not equal to 104, then this is a wrong answer} \end{gathered}[/tex]Option B
[tex]\begin{gathered} 8+a+8b \\ 8+5+8(8)=8+5+64=77 \\ since\text{ 77 is not equal to 104, then this is wrong also} \end{gathered}[/tex]Option C
[tex]\begin{gathered} 8a+8+b=8(5)+8+8=40+16=56 \\ since\text{ 56 is not equal to 104, then this is also wrong} \end{gathered}[/tex]Option D
[tex]\begin{gathered} 8a+8b=8(5)+8(8)=40+64=104 \\ \\ 104\text{ is EQUAL to 104} \\ This\text{ is correct} \end{gathered}[/tex]Therefore, the anser is