Question

СРОЧНО ПРОШУ СРОЧНО УМОЛЯЮ​

Answer 1

$26a - 39b + 49c$

Ответ:

$(5a - 11b + 28c) - ( - 21a + 28b - 21c) = 5a-11b+28c-\left(-21a\right)-28b-\left(-21c\right) =5a-11b+28c+21a-28b-\left(-21c\right) =5a-11b+28c+21a-28b+21c =26a-11b+28c-28b+21c =26a-39b+28c+21c =26a-39b+49c$