The answer is A. The earth was formed 4.54 years ago, and during those first serveral hundred million years, oceans, continents started to form.
A) Precambrian time.
Answer:
immmm ....
I know the answer but I won't tell..lolllll
Answer:
previousAddition instance variable
Explanation:
In order to accomplish this you would need to add a previousAddition instance variable. In this variable you would need to save the amount that was added at the end of the process. Therefore, if a mistake were to occur you can simply call the previousAddition variable which would have that amount and subtract it from the total. This would quickly reverse the mistake, and can be easily called from the undo() method.
I've included my code in the picture below. Best of luck.
