I am a river in North Central South America and I am located in Brazil. Who am I? PLS GIVE BETTER DETAILS!

Where does the availability of water pose the greatest problem

Find the coordinates of a if b(-9,-10) is the midpoint of ac and c has the coordinates of (-1,9)

Which barrier to economic development is shown in the following examples? i. the high rate of hiv infection in underdeveloped nations ii. the use of children as soldiers in uganda’s army in the early 2000s iii. low literacy rates in underdeveloped nations with limited exposure to adequate education a. foreign debt b. political instability c. widespread disease d. low levels of social welfare