Tính: a) 15 + 9/3b)4/9 - 5/18c) 3/5 x 5/7 d) 4/7 : 2/7

Câu hỏi :

Tính:

a) 15 +  $\frac{9}{3}$              b) $\frac{4}{9}$  - $\frac{5}{18}$                  c) $\frac{3}{5}\times \frac{5}{7}$                  d)$\frac{4}{7}$  :$\frac{2}{7}$