What you do first is add the books 42 + 85 + 69 which equals 196. Then divide 196 by 7 and you get 28 :)
Try to understand this. Hope this help. Answer for 2 only.
If we use similar triangles ( as shown in the attachment ) we will see that the line CM is also 1/4 *( yC-yD)= 1/4*(2+2) = 1/4*4 =1
Answer: y-value of that point is A)
y=1.
X + y = 180
x = 4y
Plug that in and you get: 4y + y = 180
5y = 180
y = 36
If you want the larger angle, simply plug in y to x = 4y
So: x = 4(36) = 144
The smaller angle is 36 degrees, and the larger angle is 144 degrees.