Hei! :)
[tex](x;y)=1[/tex]
[tex]a) (a;b)=12 => a=12x, b=12y\\a+b=96\\12x+12y=96\\12(x+y)=96\\x+y=8 => x=5, y=3\\=> a=12*5=60\\=> b=12*3=36[/tex]
[tex]b)(a;b)=28 <=> a=28x, b=28y\\a+b=420 \\28(x+y)=420\\x+y=15 +> x=7, y=8\\=> a=28*7=196\\=> b=28*8=224[/tex]
[tex]c) (a;b)=18 => a=18x, b=18y\\a+b=180\\18(x+y)=180\\x+y=10=> x=3, y=7\\=> a=18*3=54\\=> b=18*7=126[/tex]
[tex]d) (a;b)=21 => a=21x, b=21y\\a+b=189\\21(x+y)=189\\x+y=9 => x=5, y=4\\=> a=21*5=105\\=> b=21*4=84[/tex]
