so you have -13, then a number that's somewhere to the right of -13. imagine a number line: the negative values are on the left side of the zero, the positive values are on the right. if you're moving to the RIGHT of -13, that means that the value will be greater than -13, or in other words, -13 will be less than the new value because you moved right.
to find the number 28 units to the right of -13, you simply need to add these two numbers: -13 + 28. you add them because you're moving 28 units in the POSITIVE direction, aka you're going UP, so you want to add. -13 + 28 = 15.
now read the statements your question gave you. C and D are just straight-up false--a positive number is never less than a negative number. those are out immediately. now, the numbers you're working with are -13 and 15, so you can immediately ignore B as an answer choice, but still: A is correct because it shows the correct inequality. -13 is less than the number 28 units to the right of it, that number being positive 15.
