Answer: Angle A measures 120 while angle B measures 45.
Step-by-step explanation: First point to note is that the sum of the interior angles of a triangle is equal to 180. So if we have the three angles identified as
(12X + 12), 15 and (3X + 18) then we can derive the following expression;
12X + 12 + 15 + 3X + 18 = 180
By collecting like terms we now have
12X + 3X = 180 - 12 - 15 -18
15X = 135
Divide both sides of the equation by 15
X = 9
Therefore we substitute for the value of X into angles A and B in order to find the measurement of the angles
Angle A = 12X + 12
Angle A = 12(9) + 12
Angle A = 108 + 12
Angle A = 120
Angle C = 3X + 18
Angle C = 3(9) + 18
Angle C = 27 + 18
Angle C = 45
Therefore, angle A is 120 degrees while angle C is 45 degrees