According to this excerpt, why was the voting rights act needed to enforce the fifteenth amendment

Jim Crow voting restrictions--The South had restricted voting through literacy tests and poll taxes. This prevented many from voting. 

The 15th Amendment granted the right to vote regardless of race. However, blacks in the South were forced to take literacy tests and pay poll taxes for access to the vote. The Voting Rights Act of 1965 abolished the gates preventing or limiting votes access to blacks. 

What are the statements?