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.

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

\(=-3.5\cdot10\cdot\dfrac{1.9}{-17.5}\)

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

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

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

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

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

Cách 1 :

Tổng là:

519 + 519 = 1038

Đáp số:1038

Cách 2 :

519 + 519

= 519 x 2

= 1038

519 + 519

= 519 x 2

= 1038

519 + 519 = 1038

Chúc bạn học tốt

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

新春的3很很踩才吧?

\(7,5x:\left(9-\frac{139}{21}\right)=\frac{63}{25}\)

\(7,5x:\left(\frac{189}{21}-\frac{139}{21}\right)=\frac{63}{25}\)

\(7,5x:\left(\frac{50}{21}\right)=\frac{63}{25}\)

\(7,5x=\frac{63}{25}.\frac{50}{21}\)

\(7,5x=6\)

\(x=6:7,5\)

\(x=\frac{4}{5}\)

vậy \(x=\frac{4}{5}\)

k mk nha vì mk đang âm điểm