Stryder

Mike and John split the cost of a $270 car trip. Mike pays $20 more than John. How much did John pay? I solved it as 20x+x=270 I'm not sure if it's correct, can I please get an explanation

PLEASE HELP!!!!!! I don't understand the question! The cost (C) of photocopies is 6 cents each for first 30 and 4 cents for each one after the first 30(Use x for the total number of photocopies. Assume x> 30]

I am familiar with finding the vertex of a polynomial but I don't know how to solve this equation. Give the vertex of x^2+9 can you please explain in steps? Thank you.