Answer:
Yo veo 16. tal vez sea mas...
Step-by-step explanation:
18
Fórmula:
[tex] \frac{a(a + 1)(b)}{2} = \frac{3(3 + 1)(3)}{2} = \frac{3(4)(3)}{2} = \frac{36}{2} = 18[/tex]
