When ever there are 2 minuses no matter what type of mathematics, when you have 2 negatives it automatically = a + (POSITIVE)

so 13- -6>>>>>>>>>>= 13+ 6= 19

More Examples: 20- -10 = 20 +10

30- -29= 59

in Division = a negative times a negative = a positive, EG: -10 times -10 = 100 because the two negatives cancel each other out !

hope it helps

Since you have two negative signs together then these can be change to a plus sign:

13 - - 6

= 13+6

= 19.

So the answer is 19.

13-(-6) Multiply the minus signs

=13 + 6 (On multiplying two minus signs, you get a plus sign - * - = +)

=19