I have been studying the most general purpose developers with Metol and Hydroquinone, the so called MQ developers and I am now proposing a family of such developers, having several of them into account. I propose the introduction of the following expressions to calculate a MQ developer of this family:

Metol + hydroquinone = 10 g/liter
Sodium Carbonate = 50 - 6,67 Metol g/l
Sodium Sulfite = 100 - 10 x Hydroquinone g/l
Potassium Bromide = 1 to 3 g/l

All quantities in g/liter.

The numeric figures were estimated and they may be different or equal the values used in commercial developers.

I assumed that the sum of developing agents is a constant, developer using only hydroquinone needs only sodium carbonate and developer using just metol only needs sodium sulfite.