Two numbers that are the same distance away from zero on a number line

What is the missing constant term in the perfect square that starts with x^2 -20x

The height of a birch tree, f(x), in inches, after x months is shown in the graph below. how much does the birch tree grow per month, and what will be the height of the birch tree after 10 months? a. the birch tree grows 1 inch per month. the height of the birch tree will be 16 inches after 10 months. b. the birch tree grows 2 inches per month. the height of the birch tree will be 26 inches after 10 months. c. the birch tree grows 3 inches per month. the height of the birch tree will be 36 inches after 10 months. d. the birch tree grows 2 inches per month. the height of the birch tree will be 24 inches after 10 months.

Me : julio wears a blue shirt every 3 days. larry wears a blue shirt every 4 days. on april 11, both julio and larry wore a blue shirt. what is the next date that they will both wear a blue shirt?