bmr calculator: use values from one class/scrren - kivy

Question

I'm trying to use values from one class/scrren to multiply with another class screen but keep getting 0.
I know i probably do not carry the variable properly from one class to another but seem to have tried almost everything so if I dont get nontype error I just get 0 value when multiplying anything, like I would carry 0 from my second screen in the values which i have to input in the second screen. Any ideas? as Im brand new on kivy
.py
class SecondWindow(Screen):
ageInput = NumericProperty()
weightInput = NumericProperty()
heightInput = NumericProperty()
def info(self):
age = self.ids.ageInput.text
ageVal = int(age)
height = self.ids.heightInput.text
heightVal = int(height)
weight = self.ids.weightInput.text
weightVal = int(weight)
add = int(age) + int(height) - int(weight)
self.ids.label.text = str(add)
addVal = self.ids.label.text
print (addVal)
return ageVal, heightVal, weightVal
class ThirdWindow(Screen):
male = ObjectProperty()
female = ObjectProperty()
second = ObjectProperty()
def bmrCalc(self, button, weight):
choice = self.ids.lbl.text
if choice == "":
self.ids.lbl.text = button
self.weight = self.second.weightInput
if self.ids.lbl.text == "male":
m = 66.5
mw = 13.75 * int(self.second.weightInput)
mh = 5.003 * int(self.second.heightInput)
ma = 6.75 * int(self.second.ageInput)
print(mw)
.kv file
<SecondWindow>:
id: second
name: "second"
age: ageInput
hheight: heightInput
weight: weightInput
lbl1: label
FloatLayout:
canvas.before:
Color:
rgba: 255, 0, 0, 1
Rectangle:
# self here refers to the widget i.e FloatLay
pos: self.pos
size: self.size
Label:
text: "Calorie Intake Calculator"
font_size: 35
pos_hint: {"x": 0.3, "top": 1}
size_hint: 0.35, 0.1
Label:
text: "Enter your age"
font_size: 30
pos_hint: {"x": 0.1, "y": 0.8}
size_hint: 0.3, 0.1
TextInput:
id: ageInput
font_size: 15
multiline: False
pos_hint: {"x": 0.5 , "y":0.82}
size_hint:0.3, 0.05
Label:
text: "Enter your height(cm)"
font_size: 30
pos_hint: {"x": 0.1, "y": 0.6}
size_hint: 0.3, 0.1
TextInput:
id: heightInput
font_size: 15
multiline: False
pos_hint: {"x": 0.5 , "y":0.62}
size_hint:0.3, 0.05
Label:
text: "Enter your weight(kg)"
font_size: 30
pos_hint: {"x": 0.1, "y": 0.4}
size_hint: 0.3, 0.1
TextInput:
id: weightInput
font_size: 15
multiline: False
pos_hint: {"x": 0.5 , "y":0.42}
size_hint:0.3, 0.05
Button:
pos_hint: {"x":0.35, "y": 0.3}
size_hint: 0.3, 0.05
text: "Submit"
on_press:
root.info()
app.root.current = "third"
root.manager.transition.direction = "left"
Label:
id: label
text: "text"
font_size: 15
pos_hint: {"x": 0.7, "y": 0.1}
size_hint: 0.3, 0.2
Button:
pos_hint: {"x":0.35, "y": 0.15}
size_hint: 0.3, 0.05
text: "Back"
on_release:
app.root.current = "first"
root.manager.transition.direction = "right"
<ThirdWindow>:
id: third
name: "third"
lbl: lbl
male: male
female: female
FloatLayout:
canvas.before:
Color:
rgba: 153, 0, 0, 1
Rectangle:
# self here refers to the widget i.e FloatLayout
pos: self.pos
size: self.size
Label:
text: "Calorie Intake Calculator"
font_size: 35
pos_hint: {"x": 0.3, "top": 1}
size_hint: 0.35, 0.1
Label:
text: "Choose Your gender"
font_size: 30
pos_hint: {"x": 0.32, "top": 0.85}
size_hint: 0.35, 0.1
Button:
id: male
pos_hint: {"x":0.35, "y": 0.6}
size_hint: 0.3, 0.1
text: "Male"
on_press:
root.bmrCalc("male", "weight")
Button:
id: female
pos_hint: {"x":0.35, "y": 0.5}
size_hint: 0.3, 0.1
text: "Female"
on_press:
root.bmrCalc("female")
Label:
id: lbl
text: ""
font_size: 15
pos_hint: {"x": 0.35, "top": 0.3}
size_hint: 0.35, 0.1
Button:
pos_hint: {"x":0.35, "y": 0.1}
size_hint: 0.3, 0.05
text: "Back"
on_press:
app.root.current = "second"
root.manager.transition.direction = "right"