Answer: 6
Step-by-step explanation:
Let's start by getting the equation to slope intercept form
First simplify

Then get y by itself

In slope intercept form y=mx+b, m is the slope
In this case the slope is 6
Cos (B) = (a^2 + c^2 -b^2) / (2 * a * c)
cos (B) = (11^2 +17^2 -12^2) / (2 * 11 * 17)
cos (B) = (121 + 289 -144) / (374)
cos (B) = 266 / 374
cos (B) =
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0.7112299465
Angle B = </span></span></span>44.665 degrees
Simply it as follows:
1 + 39 = 40
2 + 38 = 40 etc
18 + 22 = 40
19 + 21 = 40
There are 19 of these plus 40 itself . . .therefore 20 of them
20 x 40 = 800
And finally the last number not used, 20
Therefore 800 + 20 = 820
Are these true and false? I think it's true for both