Answer:
m-9 = 3 is the required expression
ANSWER: The answer is c) -5 and a very happy birthday to you
First, find out x
x+15+2x+15=180
3x+30=180
3x=150
x=50
so the two angels are x+15=65(let's name is ∠5 for convenience), and ∠6= 2x+15=115
notice the two inner lines are marked as congruent, so
∠4=∠5=65
∠1=180-∠4-∠5=180-65-65=50
Name the right bottom angle ∠7, ∠3=∠7 and ∠3+∠7=the exterior angle 100 degree, therefore, ∠3=50
∠2+∠3=∠4, therefore, ∠2=∠4-∠3=65-50=15
∠1=50, ∠2=15, ∠3=50, ∠4=65
