Solve. Simplify your answer. The equation is 14x 7/8

We just started the introduction into circles and i have no idea how to do this.

How do you write y-10=2 (x-8) in standard form

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?