How does brutus justifies the assassination in his speech to the crowd

He attempts to justify his assassination of Caesar by explaining it was for the good of Rome, and it worked until Antony gave his own speech, thus turning the civilians to attempt and kill all of the conspirators.

(hope this helps!)

what are local authorities doing to fix the problem

explanation: what are local authorities doing to fix the problem

gaius cassius longinus and marcus junius brutus, former enemies of julius caesar who'd joined the roman senate, led caesar's assassination, dubbing themselves "the liberators." and the second one is   the assassination of julius caesar was the result of a conspiracy by many roman senators led by gaius cassius longinus, decimus junius brutus albinus, and marcus junius brutus. they stabbed caesar (23 times) to death in a location adjacent to the theatre of pompey on the ides of march 15 march 44 bc.