X-y =blank 2x+y=blank

The easiest way would be to use base 10 (a number over 10) so you would want to put it one of 2 ways as shown here both of these ways would mostlikly be accepted but as you move up you will want to stick to the second one because it makes it faster to do calulations. i got the second by multipying by 10 and putting it over 10 (as to not change the number) and for the first i took everything that was right of the decimal "." and put that over 10