Respuesta :

3 (2x + 1) = 21
6x + 3= 21
-3 -3
6x = 18

Divide each side by 6, and x equals 3.

3 (2(3) + 1) = 21
3 (6 + 1) = 21
18 + 3 = 21


Hope this helps! Can I please have brainliest so I can level up? Thank you!