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.
1. 22 - 3x + 7x = 4(x + 5)
22 - 3x + 7x = 4x + 20
<u> +3x +3x +3x </u>
22 + 10x = 7x + 20
<u> -7x -7x </u>
22 + 3x = 20
<u>-22 -22</u>
<u>3x</u> = -<u>2</u>
3 3
x = -2/3
2. 6(2x - 3) = 3(3 - 5)
12x - 18 = 3(-2)
12x - 18 = -6
<u> +18 +18</u>
<u>12x</u> = <u>12</u>
12 12
x = 1
3. 6x - 14 = 2(3x - 7)
6x - 14 = -3x
6x - 14 = 2(-7)
6x - 14 = -14
<u> +14 +14</u>
<u>6x</u> = <u>0</u>
6 6
x = 0
4. 6x + 3(x - 4) = 8(x - 3)
6x + 3x - 12 = 8x - 24
9x - 12 = 8x - 24
<u>-8x -8x </u>
x - 12 = -24
<u> +12 +12</u>
x = -12
4x+6<-6
-6 -6
-------------
4x<-12
Then you divide 4x on both sides so 4x divided by 4x and -12 divided by 4x. When dividing this the 4 isnt a negative so you dont flip the "<" so it stays the same. The answer would be x<-3
4/5x-8=3
move -8 to the other side and add
4/5x=3+8
4/5x=11
move 5x to the other side and multiply
4=5x*11
4=55x
4/55=x
