[tex]\displaystyle\bf\\x^{2} - y^{2} =105\\\\(x-y)\cdot(x+y)=105\\\\x-y < x+y\\\\1)\\\\+\left \{ {{x-y=1} \atop {x+y=105}} \right. \\--------\\2x=106\\\\x=53\\\\y=105-x=105-53=52\\\\2)\\\\+\left \{ {{x-y=3} \atop {x+y=35}} \right. \\--------\\2x=38\\\\x=19\\\\y=35-x=35-19=16\\\\3)\\\\+\left \{ {{x-y=5} \atop {x+y=21}} \right. \\--------\\2x=26\\\\x=13\\\\y=21-x=21-13=8[/tex]

[tex]\displaystyle\bf\\4)\\\\+\left \{ {{x-y=7} \atop {x+y=15}} \right. \\--------\\2x=22\\\\x=11\\\\y=15-x=15-11=4[/tex]

Ответ  :  Г