Ta có: 367367367367 = 367367000000 + 367367 = 367367(1000000 + 1) = 367367 x 1000001 

Tương tự: 429429429429 = 429429 x 1000001 

=> $\frac{367367367367}{429429429429}$367367367367429429429429 = $\frac{367367.1000001}{429429.1000001}$367367.1000001429429.1000001 (1)

Nhân tử và mẫu của vế trái cho 100001 tức là: $\frac{367367}{429429}$367367429429 = $\frac{367367.1000001}{429429.1000001}$367367.1000001429429.1000001 (2)

Từ (1) và (2) => $\frac{367367}{429429}$367367429429 = $\frac{367367367367}{429429429429}$367367367367429429429429 

$\frac{367367}{429429}=\frac{367}{429}\left(c\text{ùng chia cho 1001}\right)$367367429429 =367429 (cùng chia cho 1001)

$\frac{367367367367}{429429429429}=\frac{367}{429}\left(c\text{ùng chia cho 1001001001}\right)$367367367367429429429429 =367429 (cùng chia cho 1001001001)

Vì $\frac{367}{429}=\frac{367}{429}\Rightarrow\frac{367367}{429429}=\frac{367367367367}{429429429429}$367429 =367429 ⇒367367429429 =367367367367429429429429 

a) 7/15-(2/15-12/18)

=7/15-2/15+2/3

=5/15+2/3

=1/3+2/3

=1

b)(7/41- 4/9) - (3/19 + 7/41) + (4/9 - 16/19)

=7/41 - 4/9 - 3/19 - 7/41 + 4/9 + 16/19

=(7/41 - 7/41) - (4/9 - 4/9) - (3/19 + 16/19)

= -1