4.25-2.24=2(50-24)=2.26=52
phép tính là hợp số

x+ 7/5 =12/5
x=12/5-7/5
x=1

c
a

\(\dfrac{2\left(x-1\right)}{x}=1+\dfrac{2}{x\left(x-1\right)}\)( \(x\ne0,x\ne1\))
\(\dfrac{2\left(x-1\right)}{x}-\dfrac{2}{x\left(x-1\right)}=1\)
\(\dfrac{2\left(x-1\right)^2-2}{x\left(x-1\right)}=1\)
\(\dfrac{2\left(x^2-2x+1\right)-2}{x\left(x-1\right)}=1\)
\(\dfrac{2\left(x^2-2x+1-1\right)}{x\left(x-1\right)}=1\)
\(\dfrac{2\left(x^2-2x\right)}{x\left(x-1\right)}=1\)
\(\dfrac{2x\left(x-2\right)}{x\left(x-1\right)}=1 \)
\(\dfrac{2\left(x-2\right)}{x-1}=1\)

\(\dfrac{2\left(x-2\right)}{x-1}-1=0\)
\(\dfrac{2x-4-x+1}{x-1}=0\)
\(\dfrac{x-3}{x-1}=0\)
x-3=0
x=3
 

a, 25+35+76+65+22
=(65+35)+(76+22)+25
=100+100+25
=225
c , 78-23-25
=78-(23+25)
=78-48
=30
a , x-45=20 
x=20+45
x=65
b , 45 - x=20
     x =45-20
     x= 25

no sooner had he left the house the storm broke

3/5 . 17/21 +3/5  . 4/21
=3/5 . (17/21 + 4/21)
=3/5 . 1
=3/5

15/17 . 218/219  . -17/15
=15/17 .  -17/15 . 218/219  
= -1 . 218/219
= -  218/219

\(|x|< 2\)
=>-x<2   và   x<2
=> x>-2    và  x<2
=>-2<x<2
/x/>1
=>-x>1   hoặc    x>1
=> x<-1    hoặc   x>1