a/   y-1940+1200=19600

    y-1940=19600-1200

    y-1940=18400

   y=18400+1940

  y=20340

b/54678-y chia 6=32150

  y chia 6=54678-32150

  y chia 6=22528

  y=22528 nhân 6

  y=135168

Vậy y ở câu a/=20340....câu b / =135168

a: =>y=0,056:7=0,008

b: =>y=21/50:6=21/300=0,07

a, 0,008

b, 0,07

xy-2x-y=-6

=>x(y-2)-y+2=-6+2

=>(x-1)(y-2)=-4

=>(x-1;y-2)∈{(1;-4);(-4;1);(-1;4);(4;-1);(2;-2);(-2;2)}

=>(x;y)∈{(2;-2);(-3;3);(0;6);(5;1);(3;0);(-1;4)}

a: y-(4,56+6,7)=7,89
=>y-11,26=7,89

=>y=7,89+11,26

=>y=19,15

b: 45,32-(y+12,34)=17,65

=>y+12,34=45,32-17,65

=>y+12,34=27,67

=>y=27,67-12,34=15,33

a)y=55,8 : 4,5

y=12,4

b) y=25,42 x 2,5

y= 63,55

`a)`

`yxx4,5=55,8`

`y=55,8:4,5`

`y=12,4`

`b)`

`y:2,5=25,42`

`y=25,42xx2,5`

`y=63,55`

a) y=1,8:0,75=2,4
b) y=0,483:0,15=3,22
c) y=2,7+(3,48:1,45)=5,1
d) y=(0,125+0,5):0,25=0,7

\(a,y\times2,8+5,2\times y=48\\ y\times\left(2,8+5,2\right)=48\\ y\times8=48\\ y=\dfrac{48}{8}=6\\ ---\\ b,y\times12,25-y+y\times2,75=1050\\ y\times\left(12,25-1+2,75\right)=1050\\ y\times14=1050\\ y=\dfrac{1050}{14}=75\)

a: \(y\cdot2,8+y\cdot5,2=48\)

=>\(y\left(2,8+5,2\right)=48\)

=>\(8y=48\)

=>\(y=\dfrac{48}{8}=6\)

b: \(y\cdot12,25-y+y\cdot2,75=1050\)

=>\(y\left(12,25-1+2,75\right)=1050\)

=>\(y\cdot14=1050\)

=>\(y=\dfrac{1050}{14}=75\)

\(a,y\times27+y\times30+y\times44-y=10500\\\Rightarrow y\times\left(27+30+44-1\right)=10500\\ \Rightarrow y\times100=10500\\ \Rightarrow y=10500:100\\ \Rightarrow y=105\\ b,y\times285+115\times y=400\\ \Rightarrow y\times\left(285+115\right)=40\\ \Rightarrow y\times400=400\\ y=400:400\\ \Rightarrow y=1\)

\(a,\Rightarrow y\times\left(27+30+44-1\right)=10500\\ \Rightarrow y\times100=10500\\ \Rightarrow y=105\\ b,\Rightarrow y\times\left(285+115\right)=400\\ \Rightarrow y\times400=400\\ \Rightarrow y=1\)

a)\(162:y+216:y=6\)

⇔\(\left(162+216\right):y=6\)

⇔\(378:y=6\)

⇔\(y=63\)

b)\(602:y+123.2=253\)

⇔\(602:y+246=253\)

⇔\(602:y=7\)

⇔\(y=86\)

c)\(8\left(15720-y\right)=51784\)

⇔\(125760-8y=51784\)

⇔\(8y=73976\)

⇔\(y=9247\)