Bonsoir,
C.
[tex]\dfrac{\dfrac{3}{4}+\dfrac{5}{4}}{\dfrac{4}{3}-\dfrac{1}{2}}\\\\\\
= \dfrac{\dfrac{8}{4}}{\dfrac{8}{6}-\dfrac{3}{6}}\\\\\\
= \dfrac{2}{\dfrac{5}{6}}\\\\\\
= 2\times \dfrac{6}{5}\\\\
= \dfrac{12}{5} =2,4[/tex]
D.
[tex]\dfrac{\dfrac{\dfrac{2}{5}}{\dfrac{8}{15}}}{\dfrac{\dfrac{4}{7}}{\dfrac{5}{21}}}\\\\\\
=\dfrac{ \dfrac{2}{5}\times\dfrac{15}{8}}{\dfrac{4}{7}\times \dfrac{21}{5}}\\\\\\
= \dfrac{\dfrac{30}{40}}{\dfrac{84}{35}} \\\\\\
= \dfrac{30}{40}\times\dfrac{35}{84}\\\\
= \dfrac{3}{4}\times \dfrac{5}{12}\\\\
= \dfrac{15}{48}\\\\
= \dfrac{5}{16}\approx 0.3125[/tex]
