Question

$frac{a-c}{c} - frac{a-c}{a+c}$

Answer 1

((a-c)(a+c)-c(a-c))/c(a+c)=(a-c)(a+c-c)/c(a+c)=a(a-c)/c(a+c)

Answer 2

$frac{a-c}{c} - frac{a-c}{a+c} = frac{(a-c)(a+c)-(a-c)c}{c(a+c)}= \ = frac{a^2-c^2-ac+c^2}{c(a+c)}= frac{a(a-c)}{c(a+c)}$