remember when you see those two signs next to each other its “kao” which is keep add opposite so for b its 6-(-3) but you do keep add opposite so now it’s 6+3=9. for c it’s -2-(-5) and we still do kao which now it’s -2+5 different signs you subtract so now it’s 3 we always keep the sign of the higher variable and 5 is positive so the answer is positive.