Rent-stabilized tenants protested the rent hikes approved by the city’s Rent Guidelines Board on the steps of City Hall on Sunday, saying that seniors and the working poor would not be able to afford the increases. The board approved increases of 4.5 percent on one-year leases and 8.5 percent on two-year leases. An unusual supplemental rent increase was also approved for tenants who have lived in their apartments for at least six years. Those tenants will get a $45 monthly increase for one-year leases or $85 for two-year leases, whichever is highest. Tenants say the increases were approved too quickly and without public input. Housing advocates are considering challenging the Rent Guidelines Board’s handling of the increases.