X .4+X.7 +X.9=40300
=>X.(4+7+9)=40300
=>X.20=40300
=>X=2015
TK mình nhé
X*4+X*7+X*9=40300
=>X*(4+7+9)=40300
=>X*20=40300
=>X=40300/20
=>X=2015
X x (4 + 7 + 9) = 40 300
X x 20 = 40 300
X = 40 300 : 20
X = 2015
\(x\times\left(4+7+9\right)=40300\)
\(x\times20=40300\)
\(x=40300\div20=2015\)