5 is the answer. hope this helped!
The number on the left side of the decimal, write it as a large, in this case, three. The number on the right side of the decimal, write as a small number. Then put a ten under the five, and divide the two with a line. A way to remember this is - Imagine you have 3 cookies. The .5 represents a half of a cookie. You need to have all ten parts of the cookie to make a whole cookie. You'd need 5 more pieces of cookie to make 4 cookies. Hope this helps.
Use absolute value. If both signs are negative you will get a negative number. if both are positive you get positive. if the signs are different, subtract the smaller absolute value from the larger absolute value.
Greatest Common Is The More Times It Can Go In To That Number. And The Least Is The Least Many Times.