Question

determinar o valor de 3. (x-8),para x=12

Answer 1

3.(x-8) 
3.(12-8)
3.4 = 12 

Answer 2

$Para \to ~x=12\\\\\\3.(x-8)\to\\\\3. (12-8)\to\\\\ 3.4 \to\\\\ \boxed{12}$