maths question

my four grandchildren are called ben, maria, adam, tara.. their birthdays are on the 128th, 182nd, 218th and 281st days of the year respectively (except leap years) which 2 of my grandchild have their birthday on the same days of the week every year (expect leap years). the answer is adam and tara ..can some please explain why and how? im gonna go crazy

This is to do with modulus (The amount left after you divide by a number).
-The week consist of 7 days
-try all 4 numbers modulus 7:
128 mod 7 = 2
182 mod 7 = 0
218 mod 7 = 1
281 mod 7 = 1

as mod 7 of 218 and 281 is the same it mean they are on the same day of the week therefore Adam and Tara is the answer

Im not sure how clear my explanation is, if u didnt understand it please let me know