1. For subtracting integers, you have to add the opposite.
Eg. 7 - (-12) =19
For multiplying integers, if the signs are the same, the product is positive, if the signs are different, the
product will be a negative number.
Eg. 5 x (-10) = -50 -5 x (-10) = 50
Dividing has the same rule as multiplying.
Eg. 24~ (-6) = (-4) -24~ (-6) =4
For adding -1 crosses out +1.
Eg. 5 + (-2) =3