Idk this answer because no triangles are shaded.
check the picture below.
notice, a function that is decreasing, namely have a negative slope, doesn't have to be negative.
For number 15 and 16, you just have to find the absolute difference between the two points along the calibration of the protractor.
15. ∠BXC = |B - C| = |140° - 110°| = 30°
16. ∠BXE = |B - E| = |140° - 30°| = 110°
For numbers 20 and 21, apply the Angle Addition Postulate. This is when you add the individual interior angles to equate to the total angle.
20. ∠PQS = ∠PQR + ∠RQS
112° = 72°+ 10x°
x = 4
21. ∠KLM = ∠KLN + ∠NLM
135° = 47°+ 16y°
y = 5.5