Verified answer

That is not an equation. It is just the absolute value of 5x+3z. You are not clear about what you want.

Look here: http://www.wolframalpha.com/input/?i=|+5x+%2B3z+|

ℬ ℋ

'5x + 3z' is an expression that cannot be simplified further (unless you know what numbers 'x' and 'y' represent, in which case you can do 5*x + 5*y). Sorry I can't be of further assistance.