a) Implied probabilities and overround:

Fighter A (-250): 250 / (250 + 100) = 250 / 350 = **71.43%** - Fighter B (+210): 100 / (210 + 100) = 100 / 310 = **32.26%** - Overround: 71.43% + 32.26% = 103.69%, so **overround = 3.69%**