Verified answer

Ответ:

[tex]9[/tex] и [tex]6[/tex]

Объяснение:

Обозначим числа как [tex]x[/tex] и [tex]y[/tex]

Составим систему уравнений

[tex]\displaystyle \left \{ {{x+y=15} \atop {x-y=3}} \right.[/tex]

Сложим строки системы

[tex]\displaystyle \left \{ {{2x+y-y=15+3} \atop {x-y=3}} \right. \Bigg.\\\\\displaystyle \left \{ {{2x=18} \atop {x-y=3}} \right. \Bigg.\\\\\displaystyle \left \{ {{x=9} \atop {x-y=3}} \right. \Bigg.\\\\\displaystyle \left \{ {{x=9} \atop {9-y=3}} \right. \Bigg.\\\\\displaystyle \left \{ {{x=9} \atop {y=6}} \right.[/tex]