Use this formula:
K = K_0 * (1+r)^n
Insert and solve for n:
12600 = 6000 * (1+0.065)^n
n = 11.78
So about 12 quarters.
Hope that helped.
Use cosine law to solve the problem. See image attached.
What we're looking for is the length of side A (a side which is opposite with angle A).
This is the formula of cosine law
A² = B² + C² - 2BC cos A
Input the numbers
A² = 75² + 90² - 2(75)(90) cos 85°
A =

A =
First find the answer without decimals
√225= 15
2.25 has two decimal places, so therefore the square root must contain 1 decimal place.
√2.25= 1.5
Final answer: 1.5
ps -1.5 is also correct but I'm not sure if that's what your teacher wants.