Trying to loop an IntValue getting subtracted to a math.random, can I do that?

Players = game:GetService("Players")
FoStat = game.Players.LocalPlayer.FoodStat
remoteEvent = game.ReplicatedStorage:WaitForChild("StatStart")
FoodStatOn = false

remoteEvent.OnServerEvent(function()
	FoodStatOn = true
	while FoodStatOn == true do
		wait(math.random(45, 120))
		FoStat - math.random(-3, -6)
	end
end)

FoStat - math.random on line 10 keeps getting an error expecting a function call or assignment. I've read and watched a bunch of tutorials and documentation on the while true do statement, can't find the problem.

In line 10, you got 2 mistakes. First, the first argument in math.random() needs to be a smaller number but -3 is greater than -6, swap them and the first mistake should be solved. Second, you cannot do FoStat -, you have to do FoStat -= math.random(-6, -3) or FoStat = FoStat - math.random(-6, -3).