Answer:
We end up with our original number
Explanation:
Let x be our number
We increase by 100
increase = old number * 100%
increase = x*1
increase = x
New number = old number + increase
 = x+x
 =2x
Now we decrease by 50%
decrease = number *50%
 = 2x*.5
 =x
Final number = new number - decrease
 = 2x-x
 =x