Răspuns:
a)
[tex] \frac{2}{5} + \frac{3}{4} = \frac{8}{20} + \frac{15}{20} = \frac{23}{2.} [/tex]
b)
[tex] \frac{3}{7} x( \frac{2}{5} + \frac{3}{4} ) = \frac{3}{7} \times ( \frac{8}{20} + \frac{15}{20}) = \frac{3}{7} \times \frac{23}{20} = \frac{69}{140} [/tex]
c)
[tex] \frac{3}{7} \times \frac{5}{2} = \frac{15}{14} [/tex]
d)
[tex] \frac{3}{7} \times \frac{3}{4} = \frac{9}{28} [/tex]
e)
