The number of whole number is 23 through subtracting the numbers. hope it helps ☺️
Divide each side by 3. ----- n=M/3 .
Answer:
1120 combinations of four teachers include exactly one of either Mrs. Vera or Mr. Jan.
Step-by-step explanation:
The order in which the teachers are chosen is not important, which means that the combinations formula is used to solve this question.
Combinations formula:
is the number of different combinations of x objects from a set of n elements, given by the following formula.
In this question:
1 from a set of 2(Either Mrs. Vera or Mr. Jan).
3 from a set of 18 - 2 = 16. So

1120 combinations of four teachers include exactly one of either Mrs. Vera or Mr. Jan.
Because completementary angles add up to 180 degrees (angle 3 and angle 4)
and interior angles of a triangle will also add up to 180 degrees
if you compare these two facts, then angle 4 equals the 2 non adjacent interior angles