Exactly correct. Start at the conclusion you want and develop your justification around what you'd like to see removed from the current state of affairs.

Process (additive): Thesis (current state) + Antithesis (contrary obstacles) = Synthesis (goal)

Praxis (subtractive): Synthesis (current state) - Antithesis (contrary obstacles) = Thesis (goal)

Basis for this analysis below (bold = mine, italics = in original):

Sartre seeks to clarify his position by comparing and contrasting, at this point, praxis and process. He states that they are similar in that:

1. both are dialectical
2. they are defined by their movement and direction
3. they transcend the obstacles of the common group field
4. both are defined from the starting-point of a certain determination of the field of possibilities which permit the clarification of the signification of their different moments
5. both are violence, fatigue, perpetual exchange and transmutation of energy,

But, they are dissimilar in that:

6. praxis is revealed immediately by its end: the future determination of the field of possibilities is posited from the start by a projective transcendence of material circumstances: i.e. by a project. At each moment of action, it is the agent who produces himself in such or such posture, accompanied by such or such effort in terms of present givens, clarified by his future objective. This praxis is free because in a given circumstance, starting from a given need or danger, it invents its own law, in the absolute unity of its project, as mediation between the objectivity already given, and the objectification that remains to be produced.
7. the human group process is neither comparable to an avalanche or an inundation, nor comparable to an individual action. It conserves all the characteristics of individual action, except that of being the free constitution of ends, since it is constituted by the oriented action of a multiplicity of individuals. But at the same time, these characteristics receive it in the modification of passivity. Each here is presented as a passivity in action, and implies the same passivity in a ubiquity in all the heres. Praxis appears as the evanescent elsewhere.

— Reason and Violence, R.D. Laing & D.G. Cooper, 1964