North korea's economy was severely weakened in the early 1990s when

North korea's economy was severely weakened in the early 1990s when Soviet Union collapsed in 1991, leaving China as the isolated regime's only major ally.

To add, diplomatic relations between the Democratic People's Republic of Korea and the Union of Soviet Socialist Republics (the predecessor state to the Russian Federation) were first established on October 12, 1948 shortly after the Democratic People's Republic of Korea was proclaimed.

Amath expression is a collection of one or more terms, which are separated by the signs ( + , - , x , / ).example :   8+b8+b  or  a−3a−3in algebra, an equation is a mathematical statement with two expressions where, each expression is separated by an equal (=) sign. variables can be present on both the sides of the equality (=) sign and we use letters to denote such variables.example 1:   x=4+2x=4+2  , [here, we can observe that the variable is present only on one side of the equation].example 2:   2x+3=x+42x+3=x+4  , [here, we can observe that the variables are present on both side of the equation].