S is a three-digit number. Determine the digits of S from the clues. All the digits are odd. The last two digits add to make ten. The first and last digits add to make eight. The first two digits add to make twelve.

573

5 + 7 = 12

7 + 3 = 10

5 + 3 = 8

573 satisfies every requirement, which are all digits are odd (5,7, and 3), next is last two digits add up to 10 (7+3=10), then first and last digits add up to 8 (5+3=8), and last but not least the first two digits add up to 12 (5+7=12). So the 3 digits must be 573.