What are the lengths of the sides of this equilateral triangle

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

If you have the following equation, 2/3x+5/6-x=2-3/4x what would you multiply each term by to get rid of all the fractions

1) prove that 731^3−631^3 is divisible by 100 2) prove that 99^3−74^3 is divisible by 25