Помогите ребята плиииззз

1) $S _{22} = \frac{a _{1}+21d }{2}*22=(7+21d)*11\\\\(7+21d)*11=1309\\\\7+21d=119112\\\\21d= 112\\\\d=5 \frac{7}{21} =5 \frac{1}{3}$
2) $b _{3}=b _{1} *q ^{2}=25\\\\b _{6}=b _{1} *q ^{5}=0,2\\\\ \frac{b _{6} }{b _{3} } = \frac{b _{1}*q ^{5} }{b _{1} *q ^{2} } = \frac{0,2}{25} \\\\q ^{3}=0,008\\\\q= 0,2$
$b _{1}= \frac{25}{0,2 ^{2} }= \frac{25}{0,04}=625 \\\\S _{4}= \frac{b _{1}(q ^{4}-1) }{q-1} = \frac{625(0,2 ^{4} -1)}{0,2-1}= \frac{625(0,0016-1)}{-0,8} = \frac{625*(-0,9984)}{-0,8} = \frac{624}{0,8}= 780$