With sn denoting the sum of the first n terms of an arithmetic sequence, we are given that s1=9 and s2=20
a) find the 2nd term
b) calculate the common difference of the sequence
c) find the 4th term

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.

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step-by-step explanation: