Based on function transformations, the graph of y= cos(2θ), is the same as the graph of <span>y= cos(θ), with a component B of 2, in which case, it means the period is the only thing that differs
well the period for this function will then be </span>

so, the graph of is, the same as y= cos(θ), just shrunk by half horizontally
N/8 = 25/40
40n = 25 * 8
40n = 200
n = 200/40
n = 5
n/20 = 85/100
100n = 85 * 20
100n = 1700
n = 1700/100
n = 17
2/3 = 16/n
2n = 16 * 3
2n = 48
n = 48/2
n = 24
5/6 = 25/n
5n = 25 * 6
5n = 150
n = 150/5
n = 30
35+25=60
y=60
If you add the opposite side values of the triangle (not the one touching the y), you get the value of y). 35+25=y
This works because y+x= 180 and the three angles of a triangle add to 180.
The answer is a. You have the correct one highlighted I believe.
Hope this helps.