Help please if you can I would appreciate it

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.

In the pendulum formula t=2pi. read the problem on the picture ! ; $; $; ! ; ! ; ! ; )$; ! ; ! ; ! ; $; $; $! ; ! ; ); $; $$

Will mark ! (10 points also! ) if x varies inversely with y and x =6 when equals y= 10, find y when x=8 a. y=4.8 b. y=7.5 c. y=40/3 d. y=4/15