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.
Calculator 1: Calculate the percentage of a number.
For example: 87% of 55 = 47.85
Calculator 2: Calculate a percentage based on 2 numbers.
For example: 47.85/55 = 87%
Answer:
d). 3/5.
Step-by-step explanation:
The greatest common factor of 18 and 30 is 6, so we divide top and bottom of the fraction by 6:
18/30
= (18/6) / (30/6)
= 3/5.
Answer:
-1
Step-by-step explanation:
Slope formula: (y₂ - y₁) / (x₂ - x₁)
= (2 - 1) / (1 - 2)
= -1
Answer:
First you do what is inside the parentheses. 10 x 5 - 3. 50 - 3 =47. Then you multiply 47 x 5 = 235.
Step-by-step explanation:
