Answer will be option 2nd.
S(-4,7), T(-7,0), U(-1,0)
So if John gives a pen and pencil to each and all of them are over we know that the no. of pencils and pens should be the same
So we will find the LCM of 15 and 40 that is equal to 120
So John brought 120/15 that is 8 packets of pen and 120/40 that is three packets of pencils
Step 1: Convert
, which is in radians into degrees. To convert it multiply by 

900/12
75
Step 2: 75 degrees isn't on the unit circle but 45 degrees and 30 degrees is. Since 45 + 30 = 75 you can use the cosine of 45 and 30 to find the exact value
cos45 = 
cos30 =
Step 3: Add the cos45 and cos30 to get cos5pi/12

Hope this helped!
(1/2)*25 = 25/2 = 12.5
So the 1/2 of 25 is 25/2 or 12.5