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:
3y+5y=8y
8y=7(divide 8 in both sides to get y)
y=7/8
x+2y=3...but we already know the value of y, so substitute 7/8 to y
x+2(7/8)=3
x+14/8=3
x=3-14/8
=1.25