(x-5)(x+6) greater than or equal to 0

Aflute is on sale for 20% off. including the discount and 8% tax, the sales price is $216.

The volume of a sphere is increased by 6%. calculate the corresponding percentage increased in it area.

Afrequency table of grades has five classes (a, b, c, d, f) with frequencies of 3, 13, 14, 5, and 3 respectively. using percentages, what are the relative frequencies of the five classes?