Answer:
The legislative branch are involved in making of laws of the country and also for scrutiny and confirmation of appointed office holders such as judges in the judiciary arm . They can also amend some part of the constitution to revere some judgements and actions taken by the judiciary.
The legislative branch influences the executive branch by confirming or rejecting some decisions made by the President such as appointment of ministers and other members and also by ensuring proposed treaties are carefully considered.
The decisions of Congress are heavily influenced by the power of the president. One example would be the power of veto. Even if Congress passes a law in both the House of Representatives and Senate, it does not become a law until the president officially signs it. If the president vetoes (overrules) this law, then Congress must be able to override this veto with a 2/3 vote in both the Senate and House. With this in mind, Congress must ensure before passing the law that if it is vetoed that they would have the power to still make this law possible.
As commander in chief, the president has significant power of the military. Even though Congress needs to approve a declaration of war, they must consider what policies the president will implement once the country is at war.
They all formed representative governments.