To find angle $ \gamma $ use formula:
$$ \alpha + \beta + \gamma = 180^o $$After substituting $ \alpha = \frac{ 285509 }{ 10000 }^o $ and $ \beta = \frac{ 26673 }{ 500 }^o $ we have:
$$ \frac{ 285509 }{ 10000 }^o + \frac{ 26673 }{ 500 }^o + \gamma = 180^o $$ $$ \gamma + \frac{ 818969 }{ 10000 }^o = 180^o $$ $$ \gamma = 180^o - \frac{ 818969 }{ 10000 }^o $$ $$ \gamma = \frac{ 981031 }{ 10000 }^o $$