Complex Fractions: 1/6/3

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.

Anyone know? is appreciated! will mark brainliest if correct!

Acomputer store bought a program at a cost of $10 and sold it for $13. find the percent markup