Answer:
-5
Step-by-step explanation:
Fast and loose: it's a negative number, since the line is decreasing, and it's decreasing faster than the diagonal of the II-IV quadrant (y=-x) so it's a number less than -1. Slope it's thus -5 or close to it.
More rigorous: start counting the squares. A slope of [tex]\frac ab[/tex] tells you that every time you move vertically by a squares, you moved horizontally by b squares. Here to advance from 0 to 1 you went down from 2 to -3, ie you subtracted 5. Slope is -5