Répondre :
0,5 = (438,42*x) / 3*10^5
0,5*3*10^(-5)=438,42*x
438,42*x=1,5*10^(-5)
x=1,5*10^(-5)/438,42
x=3,42137*10^(-8)
x=1,5/(43842000)
x=1/29228000
0,5*3*10^(-5)=438,42*x
438,42*x=1,5*10^(-5)
x=1,5*10^(-5)/438,42
x=3,42137*10^(-8)
x=1,5/(43842000)
x=1/29228000