Răspuns :
a+b+84+d=320
a=84:7=12
d=84x2=168
12+b+84+168=320
b+264=320
b=320-264
b=56
a=84:7=12
d=84x2=168
12+b+84+168=320
b+264=320
b=320-264
b=56
a+b+c+d=320
c=84
a=84:7=12
d=2c=84x2=168
12+b+84+168=320
b+264=320
b=320-264
b=56
c=84
a=84:7=12
d=2c=84x2=168
12+b+84+168=320
b+264=320
b=320-264
b=56