Hi! So I'm new to using Twine, making a little short text-based RPG, using Harlowe. My question, which probably has a really simple answer that I've just been missing, is this: how would I change a variable by, say, minus 2 when a certain passage is reached? I have it set up so that when a combat is lost, it takes you to a "lost combat" page, but I want it so that when you get to that page, not only does it display text saying that you lost the combat, but it also takes whatever the current health variable is and subtracts 2. I tried doing (set: $health to $health-2) and (set: $health to $health minus 2), but neither worked- both set my health to "NaN" (which I can only assume stands for "Not a Number".)
Anyone know how to easily do this?