let x represent granddaughter and x +2 for grandson and together they = 12
so then we have the equation of x+2+x = 12
combine like terms 2x +2 =12
-2 from both sides to isolate x
2x=10 divide both sides by 2 to get x by itself
so we get x = 5 then add 2 +5=7
so grandson is 7 and granddaughter is 5