87. Решите уравнение: a) 3 + a = 5/9; б) x + 2 3/7 = 5 1/7.

Решение:

a) 3 + a = 5/9

\( a = \frac{5}{9} - 3 \)

\( a = \frac{5}{9} - \frac{27}{9} \)

\( a = -\frac{22}{9} = -2\frac{4}{9} \)

б) x + 2 3/7 = 5 1/7

\( x = 5\frac{1}{7} - 2\frac{3}{7} \)

\( x = \frac{36}{7} - \frac{17}{7} \)

\( x = \frac{19}{7} = 2\frac{5}{7} \)

Ответ: a) a = -22/9; б) x = 19/7.