Question

00000000000000000000000

Answer 1

$a_n = a_1+d(n-1)\\a_{30}=273-9*29\\a_{30} = -12$

$a_{10} = 273-9*9\\a_{10} = 192$

$S_n=\frac{a_{10}+a_{30}}{2}n \\S_{30} = \frac{192-12}{2}*30\\S_{30} = 180 * 15\\S_{30} = 2700$

Ответ: 2700.