Answer:
180=144+3X
X=12
Step-by-step explanation:
angles must add to 180
180=45+80+3X+19
gather like terms
subtract
36=3X
divide
X = 12
All triangles add up to 180* so we first need to add the angles
45 + 80 = 125
180 - 125 = 55
We need to have x contribute to the angle being 55*
3 + 19 = 22
55 - 22 = 33
3 x 12 + 19 = 55
x = 12
