You are 82-72 kg heavier than your brother, that is, you are 10 kg heavier than your brother, but your brother is actually 88 kg, and you are 10 kg heavier than your brother, so it is:
88+(82-72)
=88+ 10
=98
If you learned proportion last semester or this semester, it is
82:72=X:88
82*88=72X