I dont understand this

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 slope of the line that contains the points (-2,1) and (0,-3)

Solve the equation.then check your solution 8=1.88+a