Her weight = (mass) · (gravity) = (50kg) · (9.8 m/s²)
Work = (weight) · (height) = (50kg) · (9.8 m/s²) · (6 m)
Power = (work) / (time) = (50kg) · (9.8 m/s²) · (6 m) / (15 s)
Power = (50 · 9.8 · 6 / 15) · (kg · m² / s³)
Power = 196 (kg · m / s²) · (m) / s
Power = 196 Newton-meter/second
Power = 196 watts