If I understand the question, you have to get n alone. in this case, you have to subtract 7 from both sides, resulting in n (is less than) -10
-π/2 < arctan(x) < π/2
So cos(π/2) < cos(arctan(x)) < cos(0)
0 < cos(arctan(x)) < 1
Formula for compound interest is
Interest = Amount - Principal
Interest =
- P
Where r = rate in percent
t = time in years
For Jaina,
P = $300
r= 7%
t = 3 yrs
So, Interest =
- 300
For Tomas
P = $400
r= 4%
t = 3 yrs
So, Interest =
- 400
So pair of equations for Jaina and Tomas are
Interest =
- 300
Interest =
- 400
To be exact it would be 27.8 but the nearest would be 33 degrees so the answer is A