Answer:
![F_(David) = 5N](https://img.qammunity.org/2021/formulas/physics/college/tku40ppvnfr72q5o9dxizeen7dn97v8ajk.png)
Step-by-step explanation:
If the rope accelerates toward Stacy, then the force David applies is less than that of Stacy does.
By Newton’s Second Law the net force can be calculated.
![F_(net) = ma = 5*2 = 10](https://img.qammunity.org/2021/formulas/physics/college/6kwz0i6xmmj1ojstfvcmka4qmu8u77b44w.png)
In that case, David pulls with 15 - 10 = 5N in order the rope to accelerate at 2 m/s^2.