Răspuns :
(x+59)+(486-255)=987
x+59+231=987
x+290=987
x=987-290
x=697
x+59+231=987
x+290=987
x=987-290
x=697
(x+59)+(486-255)=987
(x+59)+ 231= 987
x+59 = 987-231
x+59 = 756
x = 756 - 59
x = 697
(x+59)+ 231= 987
x+59 = 987-231
x+59 = 756
x = 756 - 59
x = 697