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\(\frac{-1}{-16}-\frac{1}{15}\)
\(=\frac{1}{16}-\frac{1}{15}\)
\(=\frac{15-16}{16\times15}\)
\(=\frac{-1}{240}\)
\(-\frac{1}{16}-\frac{1}{15}\)
\(=-\left(\frac{1}{16}+\frac{1}{15}\right)\)
\(=-\frac{16+15}{16\times15}\)
\(=-\frac{31}{240}\)
2575+37-2576-29=(2575-2576)+(37-29)=-1+8=8-1=7
34+35+36+37-14-15-16-17=(34-14)+(35-15)+(36-16)+(37-17)=20+20+20+20=20.4=80
k cho mình nhá
a/2575+37-2576-29
= (2575-2576)+(37-29)
= -1+8
= 7
b/34+35+36+37-14-15-16-17
=(34-14)+(35-15)+(36-16)+(37-17)
=20+20+20+20
=80
2,
a) \(315-\left(135-x\right)=215\)
\(\Rightarrow135-x=315-215\)
\(\Rightarrow135-x=100\)
\(\Rightarrow x=135-100\)
\(\Rightarrow x=35\)
b) \(x-320:32=25\cdot16\)
\(\Rightarrow x-10=5^2\cdot4^2\)
\(\Rightarrow x-10=20^2\)
\(\Rightarrow x-10=400\)
\(\Rightarrow x=410\)
c) \(3\cdot x-2018:2=23\)
\(=3\cdot x-1009=23\)
\(\Rightarrow3\cdot x=1032\)
\(\Rightarrow x=1032:3\)
\(\Rightarrow x=344\)
d) \(280-9\cdot x-x=80\)
\(\Rightarrow280-x\cdot\left(9+1\right)=80\)
\(\Rightarrow280-10\cdot x=80\)
\(\Rightarrow10\cdot x=280-80\)
\(\Rightarrow10\cdot x=200\)
\(\Rightarrow x=20\)
e) \(38\cdot x-12\cdot x-x\cdot16=40\)
\(\Rightarrow x\cdot\left(38-12-16\right)=40\)
\(\Rightarrow x\cdot10=40\)
\(\Rightarrow x=40:10\)
\(\Rightarrow x=4\)