a)x= -142-83= -225
y=67+59+72=126+72=198
x-y= -225-198= -423
y-(-x)= 198-(-225)=198+225= 423
b)x=46+91-200=137-200= -63
y=108-415+25= -307+25= -282
x-y= -63+282= -219
y-(-x)= -282-63= -345
c)x= -228+41= -187
y= -69-54-283= -123-283= - 406
x-y= -187+406= 219
y-(-x)= -406-187= -593
