How many proper subsets are there for each set? {a, b,c}

Me what is the value of x? showing work would be appreciated - ! : )

Does the point (1, sqrt 7) lie on circle shown.

Astore has apples on sale for three dollars or 2 pounds how many pounds of apples can you buy for nine dollars if an apple is approximately 5 ounces how many apples can you buy for nine dollars