another way to put is:
if final score is Australia 1 - 0 Japan
if u bet Australia -1.5 goals, u will lose.. cuz final score australia 1 - 1.5, u get nagative score.., where else japan is 0, u will lose the bet
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if u bet Japan +1.5 goals.. u will win cuz final bet score is aus 1 - 1.5 Japan
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if aus 2 - 0 japan
if u bet Australia -1.5 goals, u will win.. cuz final score australia 2 - 1.5, u get 0.5, where else japan is 0, i.e. u will win the bet
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if u bet japan +1.5 goals, u will lose cuz final bet score is aus 2 - 1.5 japan