Is my calculation for solving this graph X is right?

What number must you add to complete the square x^2+12x=16

Aswim teacher sells lesson packages. the best deal has the highest ratio of lessons to total cost. swim lesson packagesnumber of lessons total cost$10$4010 1 $8015$80which package is the best deal? l lesson for $105 lessons for $4010 lessons for $8015 lessons for $80mark this and returnsave and exit

25 ! the line of best fit is h = 5a + 86. predict the height at age 16. show your work.