Let a1 be the acceleration of monkey while moving down.
F.B.D of monkey while moving downward

Using Newton's second law of motion,
mg−T=ma1
∴500−T=50×4⇒T=300N
Let a2 be the acceleration of monkey while moving up.
F.B.D of monkey while moving up

Using Newton's second law of motion
T−mg=ma2
⇒T−500=50×5
⇒T=750N
Breaking strength of rope =750−300=350N
∴ Rope will break while monkey is moving upward.