Vì $\frac{80}{x}$ = $\frac{120}{y}$
⇒ 80y = 120x ⇔ 2y = 3x
Ta có:
$\frac{104}{x}$ -1 = $\frac{96}{y}$
⇔ $\frac{104-x}{x}$ = $\frac{96}{y}$
⇔ (104-x). y = 96x
⇔ 104y - xy = 32.3x
⇔ 104y - xy = 32.2y
⇔ 104y - xy - 64y = 0
⇔ 40y - xy = 0
⇔ y.(40-x) = 0
⇔ $\left \{ {{y=0} \atop {40-x = 0}} \right.$
⇔ $\left \{ {{y=0} \atop {x=40}} \right.$