The equation 3 x -6x=72 has a solution between 4 and 5

Given: x + y = 6. if xe (-15, -6, -1), then which of the following sets of ordered pairs are solutions? © {(-15, -21), (-6, -12), (-1, -7)} [(-15, 21), (-6, , 7)} {(-15, 21), (-6, 12), (-1, -7)}

Mindy bought 5/8 pound of almonds and a 3/4 pound of walnuts.which pair of fraction cannot be used to find how many pounds of nuts she bought in all.

[10 points, algebra 2-simplifying complex fractions]according to my answer key the restrictions are -1 and 4. but why not positive 1?