So,
Normally a unit rate will be x per 1y. Example: 60 miles/1hr.
Therefore, the option with the denominator as 1 would be the unit rate.
The correct option is C.
Step-by-step explanation:

3x+15=0
<=> 3x=-15
<=> x= -15/3
<=> x= -5
Vậy nghiệm của đa thức 3x+15 là -5
The answer would be C, 150 televisions.