6номерпомогите плиз оформить решение!спасибо

X+72+x=216
2x=216-72
2x=144
x=72
72+72=144-занято
72-свободно

<span> арифметическая прогрессия<span><span>
116 </span> <span> 145 </span> <span> 174 </span> <span> 203 </span> <span> 232 </span> <span> 261 </span> <span> 290 </span> <span> 319 </span> <span> 348 </span> <span> 377 </span> <span> 406 </span> <span> 435 </span> <span> 464 </span> <span> 493 </span> <span> 522 </span> <span> 551 </span> <span> 580 </span> <span> 609 </span> <span> 638 </span> <span> 667 </span> <span> 696 </span> <span> 725 </span> <span> 754 </span> <span> 783 </span> <span> 812 </span> <span> 841 </span> <span> 870 </span> <span> 899 </span> <span> 928 </span> <span> 957 </span> <span> 986 </span> </span></span>

60/x = 40
x = 60/40
x = 3/2

Дано
b₃·b₇·b₉=81
По формуле общего члена геометрической прогрессии
(b₁q²)·(b₁q⁶)·(b₁q⁸)=81
(b₁)³·q¹⁶=81
(b₁q⁵)³·q=81
(b₆)³·q=81  ⇒  81=3·27  ⇒ 
q=3 
(b₆)³=27  ⇒  b₆=3