11,17,18,19,23,21,14 what is the median

If the graphs of the linear equations in a system are parallel, what does that mean about the possible solution(s) of the system? a. there are infinitely many solutions. b. there is no solution. c. there is exactly one solution. d. the lines in a system cannot be parallel.

Write two subtraction equations that are equivalent to 5 + 12 = 17.

The radius of the earth is two times the radius of the moon. what fraction of the volume of the earth is the volume of the moon?