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19)
$17°45'\,6'$$'=$
$ = 17+\dfrac{\cancel{45}^3}{\cancel{60}_4}+\dfrac{6}{60^2}=$
$= 17+\dfrac{3}{4}+\dfrac{\cancel6^1}{\cancel{3600}_{600}}=$
$= 17+\dfrac{3}{4}+\dfrac{1}{600}=$
$= 17,751\overline6°.$
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20)
$35°16'\,48'$$'=$
$= 35+\dfrac{\cancel{16}^4}{\cancel{60}_{15}}+\dfrac{\cancel{48}^1}{\cancel{3600}_{75}}=$
$= 35+\dfrac{4}{15}+\dfrac{1}{75}=$
$= \dfrac{882}{25} = 35,28°$