Solution:
The tension 56.6 Newtons.
Since the mass is 10.0 kg, the weight is 98.0 N. Each cable must pull upwards with 49.0 N of force. Thus,
sine 60° = (49.0 N) / (Ftens).
Proper use of algebra leads to the equation
Ftens = (49.0 N) / [ sine 60° ] = 56.6 Newtons