What is the missing number in the following series: 61, 57, 53, 45 a. 50 b. 49 c. 48 d. 51 (explanation would be appreciated)

Given 61, 57, 53, ... , I ask myself what the first term is. That's 61. How do I get 57 from 61? By subracting 4. From 57, how do I get 53? By subtracting 4. Thus, this is an arithmetic sequence with common difference -4.

Looking at 61, 57, 53, ___, 45 again, I ask myself what would happen if I were to subtract 4 from 53. I'd get 49. As a check, I'd subtract 4 from 49. Do I get 45? Yes.

So the missing number here is 49.

32/80  

91/140

the last one 54 doesn't go into 45. 54/100 ?

step-by-step explanation:

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.