A+(-b+c) = a-b+c
a-(-b-c) = a+b+c
m-(n+m) = m-n-m = -n
(6+x) - 1/3 = 6+x-1/3 = 6-1/3+x = 18/3 - 1/3 + x = 17/3 + x = 5 2/3 +x
-(m+n) - (-m+n) = -m-n+m-n = -2n
a-(-a-b+n) = a+a+b-n = 2a+b-n
-(-p-a)-(-k+p) = p+a+k-p = a+k
-2,9 - (-х+9,7) = -2,9 + х - 9,7 = х -12,6