Ответ:

а)4×5=20

б

[tex]( \frac{23}{11} + \frac{3}{11}) \times \frac{11}{12} [/tex]

[tex] \frac{26}{11} \times \frac{11}{12} [/tex]

[tex]13 \times \frac{1}{6} = \frac{13}{6} [/tex]

в)

[tex] \frac{1}{5} \times 3 = \frac{3}{5} [/tex]

г)

[tex] \frac{11}{12} \times 2 = \frac{11}{6} = 1 \frac{5}{6} [/tex]