When subtracting a number from a negative (like question one) the subtraction sign will now be an addition sign.
1.
6-(-7)=13
For question 2, its simple subtraction. If you subtract a negative from positive, it'l be a negative.
2.
-3 - 3= -6
3.
-15 - 23 = -38
Now we combine my previous explanations. Subtracting a negative from a negative will be like adding (like in question 4)
4.
-9 - (-5)= -4
5.
5 - (-15)=20
6.
78-(-17)=95
Extra Info:
When adding a number (doesnt matter if positive or negative) to a negative it will turn into subtraction.
Examples:
6+(-9)=-3
-9+(-9)= -18
