Giải thích các bước giải:
Ta có :
$a+b=9,85\to b=9,85-a$
$\to\dfrac{1}{10500}a+\dfrac{1}{2700}(9,85-a)=\dfrac{1}{1000}$
$\to(\dfrac{a}{10500}-\dfrac{a}{2700})+\dfrac{9,85}{2700}=\dfrac{1}{1000}$
$\to\dfrac{-13a}{47250}+\dfrac{197}{54000}=\dfrac{1}{1000}$
$\to\dfrac{-13a}{47250}=\dfrac{-143}{54000}$
$\to a=\dfrac{77}8$
$\to b=9,85-a=\dfrac{9}{40}$