The probability that a particular type of smoke alarm will function properly and sound an alarm in the

presence of smoke is 0:8. You have two such alarms in your home and they operate independently.

The probability that at least one sounds an alarm in the presence of smoke is ________.

(1) 0:96

(2) 0:36

(3) 1:00

(4) 0:8

(5) 0:64

Please explain method used as i cannot figure it out :/