( - 100) - 12
=-100+(-12)
=-112
143 - ( - 123)
=143+123
=266
( - 116) - ( -16 )
=-116+16
=-100
(-123 ) - 20
=-123+(-20)
=-143
a) ( - 100) - 12 = -( 100 + 12 ) = -112
b) 143 - ( - 123) = 143 +123 = 266
c) ( - 116) - ( -16 ) = -(116 - 16 ) = - 100
d) (-123 ) - 20 = -(123 + 20) = -143