"which issue did the virginia plan, the new jersey plan, and the great compromise address at the constitutional convention (1787)? "

They all dealt with representative government.  The Virginia plan said the number of representatives should be based on the population. The NJ plan said the number should be equal regardless of population.  The Great Compromise created a bicameral Congress, two houses.  The Senate with two representatives from each state and the House of Representatives based on population.

The statistics for the eastern war are grim. more than three-million men died in the fighting, more than nine-million men were wounded, and every major country which participated lost its form of government.