According to the information given, it is found that the third commercial was 1.233 minutes long.
The sum of the time used by the three commercials is 3, hence:
[tex]\frac{7}{6} + \frac{3}{5} + x = 3[/tex]
[tex]\frac{35 + 18 + 30x}{30} = 3[/tex]
[tex]53 + 30x = 90[/tex]
[tex]30x = 37[/tex]
[tex]x = \frac{37}{30}[/tex]
[tex]x = 1.233[/tex]
The third commercial was 1.233 minutes long.
A similar problem, in which the information given is used to build and solve an expression, is given at brainly.com/question/24812278