Answer:
y= 7^-t
Step-by-step explanation:
Equation for exponential decay:
An equation represents exponential decay if a term between 0 and 1 is elevated to the independent variable.
In this question:
First option 4 is elevated, so not exponential decay.
Second option:

, thus, the second option represents exponential decay.
If you added more context then I would probably answer your question
Answer:
Step-by-step explanation:
1.cos
2.sin
3.cos
4.tan
5.sin
6.tan
3/5x + 1/2y = 30
-3/5x. -3/5x
1/2y = -3/5x + 30
—————————
1/2
Y= -1.2x + 60