Explanation:
Since the integers are consecutive,
let the smaller one be x
then the larger will be x+1
Now their sum is -15
x+x+1=-15
2x=-15-1
2x=-16
x=-8
Therefore the smaller is -8 and the larger is -7
Now when one is added to the smaller integer it becomes -8+1=-7
If 2 is subtracted from the larger one it becomes -7-2=-9
their product therefore becomes -9×-7=63