Bonsoir
A = (0.0012 x 10^-8 x 1.5 x 10^20) / (6 x 10^4)
= [ (0.0012 x 1.5) / 6 ] x [ (10^-8 x 10^20) / 10^4 ]
= (0.0018 / 6) x [ (10^-8+20) / 10^4 ]
= 0.0003 x (10^12 / 10^4)
= 0.0003 x 10^12-4
= 0.0003 x 10^8
= 3 x 10^-4 x 10^8
= 3 x 10^-4+8
= 3 x 10^4
= 30 000
Voilà j'espère avoir pu t'aider ^^