a, Ta có:
$\color{black}{A = 101.50}$
$\color{black}{B = 50.49+53.50 = 50.(49+53) = 50.102}$
Vì $\color{black}{101 < 102}$
⇒ $\color{black}{101.50 < 102.50}$
⇒ $\color{black}{A < B}$
b, Ta có:
$\frac{27}{13}$ = 2$\frac{1}{13}$
$\frac{15}{7}$ = 2$\frac{1}{7}$
Vì $\frac{27}{13}$ < $\frac{15}{7}$ ⇒ $\frac{13}{27}$ < $\frac{7}{15}$