How to add 25 to a value and then remove 25 from the value, not change the full value?

Gyazo link

local particleem = workspace:WaitForChild("Igniterone").igniteparts.emiter.ParticleEmitter
local clickdet = script.Parent.ClickDetector
local button = script.Parent
local status = false
local sound = workspace:WaitForChild("Igniterone").igniteparts.Sound
local energyvtext = workspace:WaitForChild("EnergyPanel").Part.SurfaceGui.energyvalue
local energyvalue = tonumber(energyvtext.Text)
print(energyvalue)
local newval
local newvalstring
clickdet.MouseClick:Connect(function()
	if status == false then
		particleem.Enabled = true
		button.BrickColor = BrickColor.new("Really red")
		sound.Playing = true
		newval = (energyvalue + 24)
		newvalstring = tostring(newval)
		print(typeof(newval))
		energyvtext.Text = newvalstring
		status = true
		
	elseif status == true then
		particleem.Enabled = false
		button.BrickColor = BrickColor.new("Lime green")
		sound.Playing = false
		newval = (energyvalue - 25)
		newvalstring = tostring(newval)
		print(typeof(newval))
		energyvtext.Text = newvalstring
		status = false
	end
end)

Everything here is working except that it changes the value of energyvtext, i want it to add 25 to it and remove 25 but it doesn't, it just changes, not adds or removes.