The folding chair has different settings that change the angles formed by its parts. Suppose m∠2 is 31 and m∠3 is 65. Find m∠1. The diagram is not to scale.

Answer:
m∠2=31
m∠3=65
m∠1=?
Notice that measure of angle 2,3 and the angle that's next to angle 1 will form a triangle. Let's name the angle next to 1 to be x.
31+65+x = 180
96+x = 180
x = 180-96
x = 84
Now, you can easily find the m∠1.
84+m∠1 = 180 (REASON: Linear pair)
m∠1 = 180-84
m∠1 = 96