Answer:
115°
Step-by-step explanation:
Knowing that the sum of all interior angles of any triangle is 180 degrees, we can find the measurement of the missing angle of the triangle. The calculation is 180 - 75 - 40 = 65. Then, notice that the blue angle and the missing angle are supplementary (linear; add up to 180 degrees). So we can find the blue angle's measurement by 180 - 65, so the answer is 115 degrees.
