Find the difference in temperature between each 1000 feet:
From 1 to 2: 30 - 23.5 = 6.5
From 2 to 3: 23.5 - 17 = 6.5
From 3 to 4: 17 - 10.5 = 6.5
The temperature change is constant as it drops 6.5 degrees for every 1000 foot gain in elevation.
At 5,000 feet the temperature would be : 10.5 - 6.5 = 4
At 6,000 feet: 4 - 6.5 = -2.5
At 7,000 feet: -2.5 - 6.5 = -9
At 8,000 feet: -9 - 6.5 = -15.5
At 8,000 feet the temperature would be -15.5 degrees.
To get a close estimate, we can round 49 up to 50 and 311 down to 300, obtaining an estimate of 50/300 = 1/6, or 0.1666... as a repeating decimal. That decimal approximation is a little less than one hundredth away from the actual decimal approximation of ≈ 0.1576
First, you should solve for

, which equals

. Now, solve the integral of

=

, to get that

. You can check this by taking the integral of what you got. Now by the Fundamental Theorem
![\int\limits^2_0 {4x} \, dx=[2x^2] ^{2}_{0}=2(2)^{2}-2(0)^2=8](https://tex.z-dn.net/?f=%20%5Cint%5Climits%5E2_0%20%7B4x%7D%20%5C%2C%20dx%3D%5B2x%5E2%5D%20%5E%7B2%7D_%7B0%7D%3D2%282%29%5E%7B2%7D-2%280%29%5E2%3D8)
.
This should be the answer to your question, if I understood what you were asking correctly.
28°
a triangle = 180°
180°-140°= 40°
180°-68°= 112°
180°-112°-40°= 28°