Answer:
m<A = 120°
m<C = 45°
Step-by-step explanation:
We can use the triangle sum theorem to find the measures of the angles.
m<A + m<B + m<C = 180°
Then substitute in their given values.
12x + 12 + 15 + 3x + 18 = 180°
Now simplify the equation and you get
15x + 45 = 180°
Continue to solve
15x = 135
x = 9°
Now substitute this value of 9 for the angle expressions of <A and <C
(12 x 9) +12 = m<A
m<A = 120°
(3 x 9)+ 18 = m<C
m<C = 45°
Hope this helps. To check your answer you can add up all the answers to see if it equals 180°.
