How many elements are in a b and c

Solve the given system of equations. 2y= -x+9 , 3x-6= -15

Due to bad planning, two of the local schools have their annual plays on the same weekend. while 457 people attend one, and 372 attend the other, only 104 people were able to attend both. how many people went to at least one play?

Use the distance formula to find the distance between (-3,5) and (3,1)