Hello @Smithalmuwahidy,
How are you doing? Lets work each equation by their-self. Lets start with the first equation: [tex]a-5.1=1.7[/tex]
You would need to move all terms not including "a" to the right side of the equation. You also need to combine like terms like shown below:
[tex]a-5.1=1.7
a(-5.1+ 5.1)=(1.7+ 5.1)
a=6.8
[/tex]
Your answer is a=6.8 :)
Moving on to the second equation:
[tex]-31=z+(-17)[/tex]
You would do the same as the last equation, to get z=-14.
I hope this helped you, and if you need further help contact me.
Thank you,
Darian D.