Final answer:
From the equation M<9 = M<6 + M<8, it can be concluded that M<9 is exactly equal to the sum of M<6 and M<8, which is option A. The equation establishes a specific relationship between the angle measures.
Step-by-step explanation:
When we look at the equation M<9 = M<6 + M<8, we can interpret the relationship between the angles represented by their measures. This equation tells us that the measure of angle 9 (M<9) is exactly equal to the sum of the measures of angle 6 (M<6) and angle 8 (M<8). Therefore, the correct assumption based on this equation is A. M<9 is equal to M<6 + M<8. The other options can be dismissed: B suggests that M<9 is greater than the combined measures of M<6 and M<8, which contradicts the given equation; C mistakenly uses the term 'congruent' which relates to the angles themselves and not the measures; and D wrongly suggests that no relationship can be determined, whereas the equation clearly defines one.