Answer:
The given expression
Step-by-step explanation:
Here, the given expression is: 
Now, starting from the outer most bracket.
As we know :

and 
⇒ 

Hence, the given expression
According to the information given, the ramp would be 50 feet high. (However, that seems really high. Did you type your problem correctly?)
If you draw a picture, you will see that you can set up a cosine ratio to solve this problem. With a 30 degree angle of depression, the angle we are going to use 60 degrees.
We can set up the following equation:
cos(60) = x / 100
0.5 = x / 100
50 = x

The account will have decreased by $2640 after 2/3 year.
The answer i got is b<-18.. i’m not sure if it’s right but you could try ! :).. i’m very sorry if you get it wrong .