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

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

a, 0,008

b, 0,07

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

a: \(y\cdot2,8+y\cdot5,2=48\)

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

=>\(8y=48\)

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

b: \(y\cdot12,25-y+y\cdot2,75=1050\)

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

=>\(y\cdot14=1050\)

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

theo dõi giúp mik nhé^^

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=12.4

b.y=63.55

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

⇔\(125760-8y=51784\)

⇔\(8y=73976\)

⇔\(y=9247\)

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

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

Bài 2: 

a: \(\dfrac{4\cdot7}{9\cdot32}=\dfrac{4}{32}\cdot\dfrac{7}{9}=\dfrac{1}{8}\cdot\dfrac{7}{9}=\dfrac{7}{72}\)

b: \(\dfrac{3\cdot21}{14\cdot15}=\dfrac{63}{210}=\dfrac{3}{10}\)

c: \(\dfrac{9\cdot6-9\cdot3}{18}=\dfrac{9\cdot3}{18}=\dfrac{3}{2}\)

d: \(\dfrac{17\cdot15-17}{3-20}=\dfrac{17\cdot14}{-17}=-14\)

e: \(=\dfrac{26\cdot5}{26\cdot35}=\dfrac{5}{35}=\dfrac{1}{7}\)

f: \(=\dfrac{49\left(1+7\right)}{49}=8\)

a) (y + 5) x 2020 = 205 x 2020

(y + 5) x 2020 = 414100

y + 5 = 414100 : 2020 = 205

y = 205 - 5 = 200

a) y= 200

b) y-45600 = 1600 × 4 ×25

y-45600=160000

y= 114400

b) y - 45600 = (2019 - 419) x 4 x 25

y - 45600 = 1600 x 100

y - 45600 = 160000

y = 160000 + 45600 = 205 600

a: =>y=1,25x3,14=3,925

b: =>y:0,24=15-7,8=7,2

hay y=1,728

c: =>10y=36,7

hay y=3,67

d: =>6:y=1,5

hay y=4

e: =>4y+0,2y=44,1

=>4,2y=44,1

hay y=10,5