Question

Three commercials are played in a row between songs on the radio. The three commercials fill exactly 3 minutes of time. If the first commercial uses 1 – minutes, and the second uses 3 minute, how long is the third commercial? The third commercial is minutes long.

Answer 1

3 commercials

3 minutes

3 = 1st commercial + 2nd commercial + 3rd commercial

3 = 1 1/5 + 3/4 + 3rd commercial

3rd commercial = 3 - 6/5 - 3/4

= 60/20 - 24/20 - 15/20

= 21/20

The third commercial last = 21/20 or 1 1/20.