phép tính cứ làm bình thường nha nhân chia trước cộng trừ sau , cái gì trung đặt ra ngoài .xin lỗi vì vt hơ mỏi tay nên mik vt lời thôi nha 

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cút m*** đi!!

giúp mk nha hiện giờ mk đg cần gấp

=(1/13+12/13)+(2/13+11/13)+(3/13+10/13)+......(6/13+7/13)

=1+1+1+1+1+1

=6

\(=\frac{1+2+3+...+12}{13}\)

\(=\frac{\left(12+1\right)+\left(11+2\right)+..+\left(5+7\right)+6}{13}\)

\(=\frac{12+12+12+12+12+6}{13}\)

\(=\frac{12.5+6}{13}\)

\(=\frac{66}{13}\)

\(\frac{2}{5}+\frac{7}{12}+\frac{13}{12}=\frac{24+35+65}{60}=\frac{124}{60}=\frac{31}{15}\)

a) 12/17 + 21/25 = 657/425

b) 4 - 205/811 = 3039/811

c) 12 . 21/25 = 252/25

d) 4 : 205/811 =  205/3244

a) 12/17 + 21/25 = 657/425

b) 4 - 205/811 = 3039/811

c) 12 . 21/25 = 252/25

d) 4 : 205/811 = 205/3244

a, 13/19

b, 5

c, 31/48

d, 6/7

mình cần cách giải

\(\frac{12}{13}+\frac{2}{7}+\frac{8}{13}+\frac{5}{7}\)

\(=\frac{12}{13}+\frac{8}{13}+\frac{5}{7}+\frac{2}{7}\)

\(=\frac{20}{13}+1\)

\(=\frac{33}{13}\)

\(\frac{12}{13}+\frac{2}{7}+\frac{8}{13}+\frac{5}{7}\)

\(=\left(\frac{12}{13}+\frac{8}{13}\right)+\left(\frac{2}{7}+\frac{5}{7}\right)\)

\(=\frac{20}{13}+1\)

\(=\frac{33}{13}\)

(30+03+2004).2+x=(13+12+2004).2

2037.2+x=2009.2

4074+x=4058

x=4058-4074

x=-16

X= -16 PỢN Ạ