The work done by the heat engine is 40 kCal.
The given parameters;
To find:
The work done by the heat engine is the change in the heat energy of the engine;
W = Q₂ - Q₁
Substitute the given parameters and solve work done (W)
W = 70 kCal - 30 kal
W = 40 kCal
Thus, the work done by the heat engine is 40 kCal.
Learn more here: https://brainly.com/question/4280097