Answer :
first list the factors of 28: 1, 2, 4, 7, 14, 28
then find 2 numbers from that list that adds up to 9: 7 + 2 = 9
two factors of 28 that add up to 9: 7 and 2
then find 2 numbers from that list that adds up to 9: 7 + 2 = 9
two factors of 28 that add up to 9: 7 and 2