7 with 13 over 125 this is the mixed number form.
The answer
the question is not clear
if it is to determine how to write this phrase as a mathematics equation, it is as follow:
let be x the unknown number
so <span>ighty-seven decreased by three times a number is greater than one hundred sixty-five means 87 - 3x>165,
so we can solve it easily as 87 - 165> 3x, and then 3 x > 32, and finally the value of x is x > 32/3=10.66</span>
its odd you're in high school and you're asking this but its 9
Answer: see proof below
<u>Step-by-step explanation:</u>
Given: cos 330 = 
Use the Double-Angle Identity: cos 2A = 2 cos² A - 1

Proof LHS → RHS:
LHS cos 165
Double-Angle: cos (2 · 165) = 2 cos² 165 - 1
⇒ cos 330 = 2 cos² 165 - 1
⇒ 2 cos² 165 = cos 330 + 1
Given: 

Divide by 2: 

Square root: 
Scratchwork: 

Since cos 165 is in the 2nd Quadrant, the sign is NEGATIVE

LHS = RHS 