Question

When you add a positive and negative number how do you determine the sign of the answer?

Answer 1

It depends which number is greater. If you have -13 + 10 the result is -3. Always think that negative numbers are on the left side so as 13 is in the left side you move 10 times to the right because 10 is positive. And when you move 10 times to the right you stop at -3. Just draw a line with positives and negatives that will help a lot. Start with small numbers

Answer 2

see which one is bigger, use the sign for the bigger number, then find the difference between the numbers.
for example, +3 +(-7)
7 is bigger than 3, so use the sign for 7, which is a negative
the difference between 3 and 7 is 4, so negative 4 is the answer