×+2009supra7 = y+2010supra7,5 = z+2011supra8=k => x=7k-2009 , y=7,5k-2010 , z=8k-2011
x+y+z=720 => 7k-2009+7,5k-2010+8k-2011=720
22,5k-6030=720
22,5k=720+6030
22,5k=6750
k=6750×10supra225 (simplifici 6750 si 225 prin 225 si ramane sus 30 si jos 1) => k=300
=> x=7×300-2001 => x=2100-2009 => x=91
=> y=7,5×300-2010 => y=2250-2010 => y=240
=> z= 8×300-2011 => z=2400-2011 => z=389
Verificare: ma(x,z)=ma(91,389)
=> ma(91,389)=91+389supra2
ma(91,388)=480supra2
ma(91,388)=240=y
