Acopy machine makes 36 copies per minute. how many copies does it make in 4 minutes and 15 seconds?

There are 60 seconds in a minute. 
To find out how many copies in a second, divide 36 by 60. 
That is 0.6
Then you would calculate to see how much in 15 seconds, 
0.6 times 15
9 copies in 15 seconds

then multiply 36 * 4 to see how many in minutes
144 copies in 4 minutes

153 copies in 4 minutes and 15 seconds.

Hope this helps :)