Model 3: Joining and Leaving

04 Try it yourself Interactive

The fixed stage first, then the rest

Give both solo times and the number of days before completion that A leaves. The console computes the fixed final stage, subtracts it, solves the joint stage and adds them back. It refuses combinations where B alone would already have finished the job inside those final days — which is a real impossibility, not a rounding problem.

A 8, B 16, A leaves 4 days early

8 days total

Set the leaving gap to 0 and the model collapses to Model 1, which is a useful check that the machinery is consistent.

Press Next to work through it one step at a time.

Total units–

Joint rate–

Days–

Alone at end–

step 0 / 0