Simplify the following text for a Grade 9 native English-speaking person.
Original: The duo achieved chart success with their first single `` Walking on a Dream '' which peaked at number ten on the Australian ARIA Singles Chart and reached number sixty four on the UK Singles Chart .
Simplified: The pair achieved chart success with their first single , `` Walking on a Dream '' , which got to number ten on the Australian charts , and reached 64 on the UK Singles Chart .