What number needs to be added to both sides of the equation in order to complete the square?

Eileen purchased 3.4 pounds of apples at the total cost of $19.72. if she purchases 6.2 pounds of apples at this store, how much would it cost?

The length of a rectangular piece of land is 92 yards more than three times its width. the perimeter is 760 yards. find its dimensions.

Find the amplitude of a sinusoidal function that models this temperature variation