\(\dfrac{\left[7.5\cdot\left(-3.5\right)-2.5\cdot3.5\right]\cdot1.9}{-17.5}\)

\(=\dfrac{-3.5\left(7.5+2.5\right)\cdot1.9}{-17.5}\)

\(=\dfrac{35\cdot1.9}{17.5}=2\cdot1.9=3.8\)

=17,86

17,86

17,68

    \(x+15,7=7,2\times2,5\)
    \(x+15,7=18\) 
    \(x=18-15,7\)   
    \(x=2,3\)
    Vậy \(x=2,3\)


    \(x\times9,1+x\times1,9=26,4\)
⇔\(x\times\left(9,1+1,9\right)=26,4\)
    \(x\times10=26,4\)
    \(x=26,4:10\)
    \(x=2,64\)
    Vậy \(x=2,64\)


    \(x:12,5=48-45,66\)
    \(x:12,5=2,34\)
    \(x=2,34\times12,5\)
    \(x=29,25\)
    Vậy \(x=29,25\)


    Sửa đề:
    \(x\times9,9+x\times10=12,5\)
⇔\(x\times\left(9,9+10\right)=12,5\)
    \(x\times19,9=12,5\)
    \(x=12,5:19,9\)
    \(x=\dfrac{125}{199}\)
    Vậy \(x=\dfrac{125}{199}\)
\(#PeaGea\)

xxxx

25%x+7,5x=-21

1/4x+15/2x=-21

(1/4+15/2)x=-21

31/4x=-21

X= -21:31/4

X= -84/31

Vậy x=-84/31.

minh cung dang lam bai toan nay

7,5*x+x*3,5=39,93

(7,5+3,5)*x=39,93

11x=39,93

x=39,93/11

x=3,63. Vậy x=3,63

\(7,5x:\left(9-6\dfrac{13}{21}\right)=7.\left(\dfrac{3}{5}\right)^2\\ 7,5x:\left(9-\dfrac{139}{21}\right)=7.\dfrac{9}{25}\\ 7,5x:\left(\dfrac{189}{21}-\dfrac{139}{21}\right)=\dfrac{63}{25}\\ 7,5x:\dfrac{50}{21}=\dfrac{63}{25}\\ 7,5x=\dfrac{63}{25}.\dfrac{50}{21}\\ 7,5x=\dfrac{3150}{525}\\ 7,5x=\dfrac{207}{35}\\ \dfrac{15}{2}x=\dfrac{207}{35}\\ x=\dfrac{207}{35}:\dfrac{15}{2}\\ x=\dfrac{207}{35}.\dfrac{2}{15}\\ x=\dfrac{414}{525}\\ x=\dfrac{138}{175}\)