$\frac{4.-5-5.3}{-7.10}$ = $\frac{-35}{y-70}$ = $\frac{1}{2}$
$\frac{2.5-3.5}{7.4-8.7}$ = $\frac{-5}{-28}$ = $\frac{5}{28}$
BCNN ( 2, 28 )= 28
QĐ : $\frac{1}{2}$ = $\frac{14}{28}$
$\frac{5}{28}$ = $\frac{5}{28}$
Vì $\frac{14}{28}$ > $\frac{5}{28}$ ⇒ $\frac{4.-5-5.3}{-7.10}$ > $\frac{2.5-3.5}{7.4-8.7}$