Is this linear or non linear

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 is the logarithmic function modeled by the following table? x f(x) 9 2 27 3 81 4

Solve 2x+y=3 x+y=5 in substitution method