= 75

75

`@Neo`

`75/100 + 3/4 xx 29 +75% xx 30 + 0,75 xx 40 `

`=75/100+3/4xx29+75/100xx30+3/4xx40`

`=75/100+75/100xx29+75/100xx30+75/100xx40xx1`

`=75/100xx(29+1+30+40)`

`=75/100xx100`

`=7500/100=75/1=75`

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`75/100 + 3/4 xx 29 +75% xx 30 + 0,75 xx 40 `

`=75/100+3/4xx29+75/100xx30+3/4xx40`

`=3/4+3/4xx29+75/100xx30+3/4xx40xx1`

`=3/4xx(29+1+30+40)`

`=3/4xx100`

`=300/4=75/1=75`

________________________________________

`75/100 + 3/4 xx 29 +75% xx 30 + 0,75 xx 40 `

`=0,75+0,75×29+0,75×30+0,75×40`

`=0,75×(1+29+30+40)`

`=0,75xx100`

`=75`

`75/100+3/4xx29+75%xx30+0,75xx40`

`=3/4+3/4xx29+3/4xx30+3/4xx40`

`=3/4xx(1+29+30+40)`

`=3/4xx100=75`

20+x=40+60

\(\Rightarrow\)20+x=100

\(\Rightarrow\)x=100-20

\(\Rightarrow\)x=80

10+90=40+x

\(\Rightarrow\)100=x+40

\(\Rightarrow\)x=100-40

\(\Rightarrow\)x=60

20 + x = 40 + 60

=> 20 + x = 100

=>         x = 100 - 20

=>         x = 80

10 + 90 = 40 + x

=> 100  = 40 + x

=> x = 100 - 40

=> x = 60

a) x x 40 = 25600

x = 25600 : 40

x = 640

b) x x 90 = 37800

x = 37800 : 90

x= 420

a)5+10=30-x

=>15=30-x

=>x=30-15

=>x=15

b)10+40=90-x

=>50=90-x

=>x=90-50

=>x=40

\(5+10=30-x\)

\(15=30-x\)

\(x=15\)

\(10+40=90-x\)

\(50=90-x\)

\(x=40\)

43 x 36 + 57 x 90 + 43 x 84 +57 x30

=[43 x (36+84)] + [57 x (90+30)]

=43 x 120 + 57 x 120

=(43+57) x 120

=100 x 120

=12000

43 x 36 + 57 x 90 + 43 x 84 +57 x 30

= 43 x 36 + 43 x 84 + 57 x 90 + 57 x 30

= [43 x (36 x 84)] + [57 x (90 + 30)]

= 42 x 120 + 57 x 120

= (42 + 57) x 120

=> 100 x 120

=> 12000

          Đáp số: 12000

3^x + 3^x+2 = 90

3^x + 3^x.3² = 90

3^x(1+3²) = 90

3^x.10 = 90

3^x = 90 : 10

3^x = 9

3^x = 3²

=>x = 2

\(3^x+3^{x+2}=90\)

\(3^x\left(1+3^2\right)=90\)

\(3^x=\frac{90}{10}=9\)

\(\Rightarrow x=2\)