Im gonna cry, plz leave an explanation for your answer.

The answer is b.

The explanation: When is says a scale factor essentially it’s asking you to size up or down. More explanation: It says side a=15 and side b=6. The scale factor of 3:1 just means 3/1. Your next formula is ?=a/3 and ?=b/3 so you divide by 3. Plug it in. 15/3=5 and 6/3=2 therefore, your answer is side a=5, and side b=2

3:1->3/1=3
A/3; B/3
15/3;6/3
5;2