On day one she starts of with 1 hour so it will be 1+30x. X being the number of days so by the seventh day Anna would practice for 240 minutes.
union=( -2,-1,0,1,2,5,7,8) intersection= -1,1
A plastic skeleton is
Answer: B. a physical model.
The world has lots of different kinds of models. A mathematical model might be a ball travels according to the equation 
. This isn't that. A computer model would be a program that somehow simulates a skeleton in the computer, this isn't that either. Our skeleton is an actual physical model just like a model airplane.
