Help ill give brainliest fill the gray spaces and red space

What is the measure of x, in degrees

You are on a cycling trip around europe with friends. you check the weather forecast for the first week. these are the temperatures for the week. sun mon tues wed thurs fri sat 16°c 20°c 24°c 28°c 28°c 23°c 15°c what is the mean temperature forecast for the week?

Could somebody me with this radical simplification?