X x 4 + X x 7 + X x 9 = 40300
X x ( 4 + 7 + 9) = 40300
X x 20 = 40300
X = 40300 : 20
X = 2015
Vậy X = 2015
\(x\cdot4+x\cdot7+x\cdot9=40300\)
\(x\cdot\left(4+7+9\right)=403000\)
\(x\cdot20=40300\)
\(x=40300:20\)
\(x=2015\)
\(x\cdot4+x\cdot7+x\cdot9=40300\)
\(x\cdot\left(4+7+9\right)=403000\)
\(x\cdot20=40300\)
\(x=40300:20\)
\(x=2015\)
X x 4 + X x 7 + X x 9 = 40300
X x (4+7+9)=40300
X x 20=40300
X=40300 : 20
X=2015