Answer:
See Explanation
Step-by-step explanation:
[tex]15 = 3 \times \bold{ \red{ \boxed5}} \\ \\ 40 = 2 \times 2 \times 2 \times \bold{ \purple{ \boxed5}} \\ \\ common \: factor \: of \: 15 \: and \: 40= 5 \\ \\ \therefore \: gcf \: of \: 15 \: and \: 40 = 5[/tex]