Answer:
ok this is what I think the first child we'll take his or her age to beX the second child will be x+ 2 and the third child will be x + 4 so it's means to get the ages you have to add all of them and quit it to 21 so it will be x + x + 2 + x + 4 is equals to 21 collect the like terms x + x + x + 2 + 4 is equals to 21 3x + 6 is equals to 21 sum of 6 over the equals sign to have 3x is equals to 21 - 6 3 x is equals to 15 divide both sides by 3 so x is 5 then substitute