a)
a - (b+c) * d
- a * + b c d
a b c + d * -
b)
a - (b - (c - d))
- a - b - c d
a b c d - - -
c)
(a - b) * (c - d)
* - a b - c d
a b - c d - *
a)
a - (b+c) * d
- a * + b c d
a b c + d * -
b)
a - (b - (c - d))
- a - b - c d
a b c d - - -
c)
(a - b) * (c - d)
* - a b - c d
a b - c d - *