Question

According to the U.S. Geological Survey, the Mississippi River is 200 mi shorter than the Missouri River. Together, they cover a total of 4880 mi. Find the lengths of each river.

Answer 1

I: missouri=mississippi+200
II: missouri+mississippi=4880

-> substitute missouri with mississippi in II:
mississippi+200+mississippi=4880
2*mississippi=4680
mississippi=2340 mi

-> insert in I to calculate missouri:
missouri=2340+200=2540 mi