easy !
fr this we need to knw sm basics :
- and - makes + (case 1)
- and + makes - (case 2 ) vice versa
and + and + makes +
with these we can solve it 1) - 13 - 5 , here its the first case
so it becomes 13 + 5 = 18 and the answer will be negative as the bigger number 13 has negative sign so the answer is -18
next -12-(-3) first we need to take off the brackets using first case so we get -12+3 , now if u c we got the 2nd case
so, it becomes 12-3 = -9
answer is negative as greater number 12 is negative