Is a percent increase for 50 to 70 = to the percent decrease from 70 to50

Tom wants to order tickets online so that he and three of his friends can go to a water park the cost of the tickets is 16.00 per person there is also a 2.50 one-time service fee for ordering tickets online write an expression in term of n that represents the cost for n ordering tickets online

You paid 28.00 for 8 gallons of gasoline. how much would you pay for 15 gallons of gasoline?

Bob is putting books on a shelf and takes a break after filling 18 1/2 inches on the book shelf. the book shelf is now 2/3 full. how long is the entire bookshelf?