How to solve mentally

Step-by-step explanation:

1.The "9-trick".To add 9 to any number, first add 10 and then subtract 1

2.Double +1

3.use adittion facts when adding bigger number.

4.subtract by adding

5.five times a number

6.four and eight times a number

7.multiply in parts

im good in math

a variable is any characteristics, number, or quantity that can be measured or counted. a variable may also be called a data item. hope i !

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.