Pls tell me which one and the question is which is a function

Find the domain of the function  [tex]f(x) = \sqrt{3x - 7} [/tex]in interval form, the domain of f is what? in advance.

Find x & pleeeeaaaassseeee me !

The frequency table shows the results of a survey comparing the number of beach towels sold for full price and at a discount during each of the three summer months. the store owner converts the frequency table to a conditional relative frequency table by row. which value should he use for x? round to the nearest hundredth. 0.89 0.90 0.92 0.96