a/ A= ( a + b ) - ( a - b ) + ( a - c ) - ( a + c )
= a + b - a + b + a - c - a - c
= ( a - a + a - a ) + ( b + b ) + ( - c - c )
= 2b + ( -2c )
= 2b - 2c
b/ B= ( a + b - c ) + ( a - b + c ) - ( b + c - a ) - ( a - b - c )
= a + b - c + a - b + c - b - c + a - a + b + c
= ( a + a + a - a ) + ( b - b - b + b ) + ( - c + c - c + c )
= 2a
a) A=a+b-a+b+a-c-a-c
A=2b
b)B=a+b-c+a-b+c-b-c+a-a+b+c
B=4a+b