a) $$34b + 26 + 17b = 34b + 17b + 26 = b(34 + 17) + 26 = 51b + 26$$
б) $$18 \cdot p \cdot 50 = 18 \cdot 50 \cdot p = 900p$$
Ответ: a) 51b + 26; б) 900p