Mathematically dilemma of life: Does a + b always equal c?

Am I being illogical in assuming life is logical? My mind wants to assume that the left side of the equation should always equal the right (and vice versa). Take this to it's logical conclusion, and the actions/events of life lead to results, and the results are the summation of actions/events. Call me simplistic, but I'm not the only one...and I guarantee you do it too.

There was recently a shooting here in Danville, not exactly your high crime community. Put this in the logicameter ... (drugs + bad choices) = shooting/death. Easy peesy, lemon squeezy. I'm sure I could add to the actions/events with more facts, but what is more lacking and unknown is the result, the right side in this equation.

I suppose these are the "when God doesn't make sense moments" in life. When we see the answer and yet fail to understand. Why did so-and-so get taken so soon? Why am I blessed/cursed in situation x when I've done y? I don't always understand, and when I do, perhaps I don't.

So, I leave you with this, from William Cowper, "God moves in mysterious ways"
"His purposes will ripen fast,
Unfolding ev'ry hour;
The bud may have a bitter taste,
But sweet will be the flow'r."