Tons of points please answer soon like in the next few minutes:)

Determine if the equation defines y as a function of x: 2xy = 1. yes o no

You went to a restaurant and spent $53.25 on the meal. there was a 6% sales tax. what was the amount of money, not including a tip, you spent at the restaurant?

The salesperson earns a 5% commission on the first $5,000 she has in sales. the salesperson earns a 7.5% commission on the amount of her sales that are greater than $5,000. this month the sales person had $8,000 in sales. what amount of commission, in dollars, did she earn?