Answer
Percentage is total points made divided by total points made and missed, hence:
Alex Brailsford: $\frac{15+5}{15+15+5+15} = 20/50 = 40%$
Rickie Jackson: $\frac{30+65}{30+65+29+130} = 95/254 = 37.40%$
Work Step by Step
as given above