Odpowiedź :
Hej!
A)
4(ac + 5a) + (-20a - 6c²) + 3c(5a + 2c) =
= 4ac + 20a - 20a - 6c² + 15ac + 6c² =
= 19ac
B)
5t(3t - 4x + 2) - 2z(-9 + 5t) + 20tz² =
= 15t² - 20tx + 10t + 18z - 10tz + 20tz² =
= 20tz² + 15t² - 20tx + 10t + 18z - 10tz
Pozdrawiam! - Julka