Решите,очень нужноо( 7-8 класс

1) $\frac{c}{c^{2}-b^{2}} : \frac{1}{c+b} - \frac{b}{c-b} = \frac{c(c+b)}{(c-b)(c+b)*1} - \frac{b}{c-b} = \\ = \frac{c}{c-b} - \frac{b}{c-b} = \frac{c-b}{c-b} =1$
2) $\frac{7ac^{2}}{a^{2}-4c^{2}} * \frac{a-2c}{ac} = \frac{7ac^{2}*ac}{(a-2c)(a+2c)*(a-2c)} = \\ = \frac{7a^{2}c^{3}}{(a-2c)^{2}(a+2c)}$
при a=5,4
c=2,2 получим
$\frac{7*5,4^{2}*2,2^{3}}{(5,4-2*2,2)^{2}(5,4+2*2,2)}= \frac{7*29,16*10,648}{1^{2}*9,8} = 221,78$