If 2+3+6+9=21 then does 7x3=21?

Which equation and solution can be used to solve this problem? thirteen less than a number is sixteen. 13-n=16: add 13 to both sides. the answer is 29. n+13=16: subtract 13 from both sides. the answer is 3. n+16=13 subtract 13 from both sides. the answer is 3. n-13=16: add 13 to both sides. the answer is 29.

What are correct trigonometric ratios that could be used to determine the length of ln

What number should be added to the expression x^2+3x+ in order to create a perfect square trinomial? 3/2 3 9/4 9