How would I change this to make the Humanoid lose a random amount of health?

Hi, at the moment this script will work but when my character touches the brick it sometimes loses health or gains health. I have tried making the numbers both negative but that just errors. So, I would appreciate it if anyone could help me with this?

script.Parent.Touched: connect(function(hit)
	local humanoid = hit.Parent:FindFirstChild("Humanoid")
	if humanoid ~= nil and humanoid.Health > 0 then
		local f = Instance.new("Fire", hit.Parent)
		f.Color = Color3.new(0, 85, 255)
		humanoid.Health = math.random(35, 100)
		
	end

end)

Make the humanoid take damage

humanoid:TakeDamage(math.random(35,100))