а) \(4.53+5\frac{5}{11}+2.47=7+5\frac{5}{11}=12\frac{5}{11}\).
б) \(8\frac{3}{5}+2.51+1\frac{2}{5}=10+2.51=12.51\).
Ответ: а) \(12\frac{5}{11}\); б) \(12,51\).