There are two forces on the mass:
-- the force of gravity downward ... (10kg) x (9.8 m/s²) = 98 newtons downward
-- the tension in the rope upward ... 118 newtons upward 
The NET force on the mass is (118 - 98) = 20 newtons upward .
 F = M a
Divide each side by 'M' : a = F / M
 a = (20 newtons upward) / (10kg) 
 a = 2 m/s² upward