To attain majority rule, two political parties merged their seats in parliament to enable
them form government. Such a government is called...

A Coalition Government

Explanation:

A coalition government is a system of governance whereby two or more political parties come together as one to enable it attain majority rule in government. The major reason for the coalition is to enable the the co-joined political party gain political power since an independent political power would not be able to gain power on its own. Classical example of countries where coalition governments  have succeeded include the government Australia, India, America,  Finland, etc.

i honestly speaking this is too long

the structure of state governments are determined by. "state constitutins'

under the us constitution, all state governments are.'republics'