I think it’s B but im not sure

19

Step-by-step explanation:

-9b -5 -7b = -309

-16b - 5 = -309

16b = 309 - 5

16b = 304

b = 304 ÷ 16

b = 19

what is the original number? you forgot to add it.

54 kilometers per hour

step-by-step explanation:

according to rules:

1 km = 1000 meter

which means that 1 meter = 1/1000 km

1 hour = 3600 second [ as 1 hour = 60 min = 60 *60 seconds ]

which means that 1 second = 1/3600 hour

therefore, 1 kilometer/hour =

thus to convert 15 meter per second to kilometer per hour, we multiply 15 to 3.6 kilometer/hour.

15 meter/second=   which is the required answer.