How does each branch(executive, legislative, judicial) check and balance the other?

The legislative branch makes laws, but the President in the executive branch can veto those laws with a Presidential Veto. The legislative branch makes laws, but the judicial branch can declare those laws unconstitutional.

the triple alliance. germany and austria-hungary were already allies by 1879 when, worried about a threat from russia, they formed the dual alliance. italy joined the group in 1882. there was a concern about a possible attack from france and the alliance needed powerful friends to defend it.