Suma

Suma
 

How do we say la suma de ambos when we talk about the time we spend on cooking, if we want to say all told la suma de ambos , lunch and dinner I spend 70 minutes.

I spend a total of 70 minutes on cooking lunch and dinner
In total, I spend 70 minutes ....

You can even use the direct translation
I spend a sum of 60 minutes ....

y para restar como se dice? Por ejemplo
Para restar el tiempo que paso en la cama, paso menos tiempo cocinando.

To leave me more time in bed...

(although I have never heard restar used before. I would use dejar.)

I don´t know it maybe contrarestar.