it is log ratio, he changed 2^x+2^y=640 //2^x => 1+2^y/2^x=640/2^x => now lets simply use pow rules 1+2^(y-x)=640/2^x //* 2^x => 2^x(1+2^(y-x))=640 => 1=2^0 => 2^x*2^(y-x)=640 ✌️🧑‍🎓🫵💪 [...] Read more