SOLUTION: Help. My Grade 7 daughter a a math question that seems to require a linear equation, but they haven`t studied it. How can I help her with this: If there are 399 students in a class

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: Help. My Grade 7 daughter a a math question that seems to require a linear equation, but they haven`t studied it. How can I help her with this: If there are 399 students in a class      Log On


   

Question 347400: Help. My Grade 7 daughter a a math question that seems to require a linear equation, but they haven`t studied it. How can I help her with this: If there are 399 students in a class, and each shakes hands with everyone else, how many handshakes will there be.
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
each of the 399 students shakes hands with the other 398 students

BUT ..... C shaking hands with D is the same as D shaking hands with C

so the total number of shakes is ___ 399 * 398 / 2