3. а) 3 5/18 : 59/60 + 2,6; б) (2 12/13 − 1 9/52) · (1,4 + 3,8);

1. а) \(3\frac{5}{18}=\frac{59}{18}\).
   \(\frac{59}{18}:\frac{59}{60}=\frac{59}{18}\cdot\frac{60}{59}=\frac{10}{3}\).
   \(\frac{10}{3}+2.6=\frac{10}{3}+\frac{13}{5}=\frac{50+39}{15}=\frac{89}{15}=5\frac{14}{15}\).
2. б) \(2\frac{12}{13}=\frac{38}{13}=\frac{152}{52}\), а \(1\frac{9}{52}=\frac{61}{52}\).
   \(\frac{152}{52}-\frac{61}{52}=\frac{91}{52}=\frac{7}{4}\).
   \(1.4+3.8=5.2=\frac{26}{5}\).
   \(\frac{7}{4}\cdot\frac{26}{5}=\frac{91}{10}=9.1\).

Ответ: а) 5 14/15; б) 9,1.