$24,5-(y:4+y\times 6)=3,5$

$(y\times \frac{1}{4}+y\times 6)=24,5-3,5$

$y\times \frac{1}{4}+y\times 6=21$

$y\times (\frac{1}{4}+6)=21$

$y=21:(\frac{1}{4}+6)$

$y=\frac{84}{25}$

🙏🙏🙏 

y=3,28 nhé

24-(Y:4+Yx6)=3,5

24-(Yx0,25+Yx6)=3,5

24-Yx(0,25+6)=3,5

24-Yx6,25=3.5

Yx6,25=24-3,5

Yx6,25=20,5

Y=20,5:6,25

Y=3,28

`#hungg`

`24-(y:4+y xx 6)=3,5`

`y xx 0,25 + y xx 6 =24-3,5`

`y xx(0,25+6)=20,5`

`y xx 6,25=20,5`

`y=20,5:6,25`

`y=3,28`

3,36 nha

(312-y) :12,6=24,5

=> 312-y = 24,5 x 12,6

=> 312 - y = 308,7

=> y = 312 - 308,7

=> y = 3,3

tìm y

( 312 - y ) : 12,6 = 24,5

( 312 - y ) = 24,5 x 12,6 

( 312 - y ) = 308,7

y = 312 - 308,7

y = 3.3

\(\left(312-y\right):12,6=24,5\)

\(312-y=24,5\times12,6\)

\(312-y=308,7\)

\(y=312-308,7\)

\(y=3,3\)

=>y*1,1+y*2+y*4-y*0,1=24,5

=>y*7=24,5

=>y=3,5

a: y=x+15-3x=-2x+15

x thuộc (-3;5) nên -2x thuộc (-10;6)

=>\(y\in\left(5;21\right)\)

y max=21 khi x=5

b: y=6x-x^2=-x^2+6x

x thuộc (0;6) nên -x^2 thuộc (-36;0)

6x thuộc (0;36)

=>-x^2+6x thuộc (-36;36)

y max=36 khi x=6