Answer:
66
Step-by-step explanation:
If there are <em>n</em> students, then the number of pairs is 
.
With 12 students, 
pairs can be formed.
The reason the formula works is this: Each of the 12 students can be paired with 11 other students (no student is paired with him/her self). But counting 12 x 11 = 132 counts each pair <u>twice</u>. Example: student A can be paired with student B,..., student B can be paired with student A. The pair was counted two times.
See the attached image that shows pairings of 5 students. There are
5(5 - 1)/2 = 5(4)/2 = 10 pairs.
Answer:
Step-by-step explanation:
Expand the brackets.
Add -9x and 5x
Add 4x and 6x on both sides.
Add the like terms.
Divide 12 into both sides.
<span> add</span><span> up the two equivalent fractions </span>
<span>Add the two equivalent fractions</span><span> which now have a common denominator</span>
<span>Combine the numerators together, put the sum or difference</span><span> over the common denominator then reduce to lowest terms if possible. tell me if this helped you.</span>
Is that the full question? I can't solve it if s is a variable
<span>The number 8.5 is being added. </span>
