Answer:
you basically do the same things just backwards
Step-by-step explanation:
for example 9+9=18 well to double check your work all you do is flip to equation 18-9=9
3
The period is the amount it time it takes to make one complete cycle. If we start at 0 for simplicity sake, the graph is at its maximum point. It reaches its maximum point again at 3, this is one complete cycle and thus the period is 3.
That you owe someone some money
sometimes i use a thingy called calculator soup and it should have a measurement calculator