$\dfrac{3}{4}+\dfrac{2}{3}+\dfrac{3}{12}$
$=\dfrac{9}{12}+\dfrac{8}{12}+\dfrac{3}{12}$
$=\dfrac{9+8+3}{12}$
$=\dfrac{20}{12}$
$=\dfrac{5}{3}$
$\dfrac{47}{15}+\dfrac{40}{16}-\dfrac{4}{30}-\dfrac{6}{17}$
$=\dfrac{94}{30}+\dfrac{5}{2}-\dfrac{4}{30}-\dfrac{6}{17}$
$=\dfrac{94}{30}-\dfrac{4}{30}+\dfrac{5}{2}-\dfrac{6}{17}$
$=\dfrac{90}{30}+\dfrac{85}{34}-\dfrac{12}{34}$
$=3+\dfrac{85-12}{34}$
$=3+\dfrac{73}{34}$
$=\dfrac{175}{34}$
