How can i prove these two convergence theorem?

Well, given that an converges to a and bn converges to b, you could "guess" the limits of the other series and then try to prove that they actually are the limits from the definition.

E.g. you can try to show that
[tex]\forall_{\epsilon > 0} \exists_{N_+} : n > N_+ \implies |(a_n + b_n) - L| < \epsilon[/tex]
where L = a + b is the postulated limit. Of course you already know that given such an [itex]\epsilon[/itex] you can find N_a and N_b such that
[tex]n > N_a \implies |a_n - a| < \epsilon[/tex]
and
[tex]n > N_b \implies |b_n - b| < \epsilon[/tex]