Odpowiedź :
Hej!
(2 + a + a + 2) : 3 = 4
2 + a + a + 2 = 4 * 3
2a + 4 = 12
2a = 12 - 4
2a = 8 / : 2
a = 4
a - 1 = 4 - 1 = 3
Odp. D
Pozdrawiam! - Julka
[tex]\frac{2 + a + (a+2)}{3} = 4 \ \ /\cdot3\\\\2a+4 = 12\\\\2(a+2) = 12 \ \ /:2\\\\a + 2 = 6\\\\a-4 = 0 \ \ |+3\\\\a - 1 = 3\\\\Odp. \ D.[/tex]