145 is 3 standard deviations above 103, since the difference, 42, is 3 times 14.
The rule I suppose is 68-95-99.7 the last number meaning 99.7% of the area of the Gaussian is between -3 and +3 standard deviations.
That's 0.3% leftover, 0.15% in each tail so
Answer: 99.85%
of the scores are (expected to be) less than 145.