Question

Help me please l’m correct or wrong?

Answer 1

No, you have to calculate their half-lives.
half-life = elapsed time * log(2) / [log (begin amount / end amount)]

Isotope A goes from 100% to 10% in 33 days
half-life = 33 days * log(2) / [log (100% / 10%)]
half-life = 33 * 0.30102999566 / 1
half-life = 9.9339898568 days

Isotope B goes from 100% to 10% in 43 days
half-life = 43 days * log(2) / [log (100% / 10%)]
half-life = 43 * 0.30102999566 / 1
half-life = 12.9442898134 days

Difference = 3 Days

Source:
http://www.1728.org/halflife.htm

Answer 2

I think   you'r right  but I cant see the quitction