Answer:
D. 7
Step-by-step explanation:
To find out the lesser number, we can go off the given information 3 less than of the other number, meaning we can add three to each answer choice to find the second number and see if those numbers have a sum of 17.
3 + 3 = 6
6 + 3 = 9
incorrect
5 + 3 = 8
8 + 5 = 13
incorrect
12 + 3 = 15
15 + 12 = 27
incorrect
7 + 3 = 10
10 + 7 = 17
correct
Thus, the answer is D.
hope this helps!