Ответ:

/7

1) а =1;2

Т. К. 1/4=3/12

2)

1/3=5/15

3/5=9/15

Следовательно а=6,7,8

/8

[tex] (x + 4.2) - 5 \frac{1}{2} = 3 \frac{7}{50} \\ x + 4.2 = 3 \frac{7}{50} + 5 \frac{25}{50} \\ x + 4.2 = 8 \frac{32}{50} \\ x = 8 \frac{32}{50} - 4\frac{2}{10} \\ x = 8 \frac{32}{50} - 4 \frac{10}{50} \\ x = 4 \frac{22}{50} [/tex]