Where is the model. To answer I need the model.
{ 1,-3,9...}
an = a1 * r^(n-1)
a1 = first term = 1
r = common ratio = -3
so ur formula is : an = 1 * -3^(n-1)
A) All triangles add up to 180° so when given two angles, add those up and subtract them from 180° . That will give you the missing angle.
3-5) When you do A above, and receive the measurement of angle 1, it will also equal 2 and you can repeat A for missing angle 3
6-8) Find the missing angle next to 1, and then subtract that from 180°. That number is the answer for 1. 2 is 55 as its a complimentary (i think thats the right term) angle. Which means it is on the opposite side of an angle. I don't remember how to find 3 however, its been a few years since I've done triangles.
X + 2 = 3/5(10) - 3
x + 2 = 6 - 3
x + 2 = 3
x = 3 - 2
x = 1 <=== ur number