When you solve the slope intercept of x + 2y = 16, and get the slope of -0.5, where does the -x come from when switching from standard to y = mx + b form? I attempted doing the problem using this:
x + 2y = 16 ---> 2y = x + 16

But apparently the correct equation to use is:
2y = -x + 16

So where does -x come from if the x is positive?