Answer:
.
Step-by-step explanation:
The given expression is

It can be rewritten as

![[\because \cos^{-1}(-x)=\pi-\cos^{-1}(x), x\in [-1,1]]](https://tex.z-dn.net/?f=%5B%5Cbecause%20%5Ccos%5E%7B-1%7D%28-x%29%3D%5Cpi-%5Ccos%5E%7B-1%7D%28x%29%2C%20x%5Cin%20%5B-1%2C1%5D%5D)
![2\left [\pi-\cos^{-1}\left(\cos \frac{\pi}{4}\right)\right]](https://tex.z-dn.net/?f=2%5Cleft%20%5B%5Cpi-%5Ccos%5E%7B-1%7D%5Cleft%28%5Ccos%20%5Cfrac%7B%5Cpi%7D%7B4%7D%5Cright%29%5Cright%5D)
![2\left [\pi-\frac{\pi}{4}\right]](https://tex.z-dn.net/?f=2%5Cleft%20%5B%5Cpi-%5Cfrac%7B%5Cpi%7D%7B4%7D%5Cright%5D)
![2\left [\frac{4\pi-\pi}{4}\right]](https://tex.z-dn.net/?f=2%5Cleft%20%5B%5Cfrac%7B4%5Cpi-%5Cpi%7D%7B4%7D%5Cright%5D)

Hence, the exact value of given expression is
.
12.93
Use inverse operations
9.27+3.66=12.93
Answer:
-10
Step-by-step explanation:
<span>The factors of 18 are 1, 2, 3, 6, 9, 18.</span>
Factor: 20k+50
since you see there is a multiple of 10 you can do…
10(2k+5)
next you look if you can factor anything else as you can see you cannot so…
10(2k+5) is you answer