Simplify the following text for a Grade 9 native English-speaking person.
Original: The London Assembly is an elected body , part of the Greater London Authority , that scrutinises the activities of the Mayor of London and has the power , with a two-thirds majority , to amend the mayor 's annual budget .
Simplified: The London Assembly is an elected body and part of the Greater London Authority that verifies the activities of the Mayor of London . It has the power , with a two-thirds majority , to amend the Mayor 's annual budget .