Angle 1, 4, 5 and 8: Since 1 and 4 are on the opposite sides of each other, 1 ~ 4. When you look at the bottom set of numbers, you'll notice that they are set up the same way as the top set of numbers. Therefore, we can say that 1 ~ 5 and 1 ~ 8. Since 1 = 40, angles 4, 5 and 8 must also equal 40.
Angle 2, 3, 6 and 7: In order to find these angles, we need to do 180 - 40, which equals 140. The reason why is because a line is equal to 180°. Angles 2, 3, 6 and 7 equal 140.
I hope this helped!