Alarm A beeps every 15 seconds.
Alarm B beeps every 25 seconds.
Both alarms beep at the same time.
Work out how long it will take for both alarms to beep at the same time again.
59 exam-style questions on Edexcel GCSE Maths Prime Factors, HCF and LCM. Each one has a worked solution and a mark scheme showing where the marks go.