What is the? A symbol which represents any number from a given replacement set

answer pls

Sam claims that cos x =sin y if x and y are congruent angels. is sam correct ?

Mrs. avila is buying a wallpaper border to go on all of her kitchen walls. she wants to buy 5 extra feet of wallpaper border than she needs to be sure she has enough. she buys 55.5 feet of the border. the store owner selling the border uses the width of mrs. avila's kitchen to determine that the length of her kitchen must be 14.5 feet.

Travis and paula went to lunch. travis ordered a sandwich for $7.50 and paula ordered a burger for $5.25.after lunch, they left a 15% tip for the waiter. how many money did they spend altogether?