Đề đúng
\(\frac{a}{b+c+d}+1=\frac{b}{a+c+d}+1=\frac{c}{a+b+d}+1=\frac{d}{a+c+b}+1\)
\(\Leftrightarrow\frac{a+b+c+d}{b+c+d}=\frac{a+b+c+d}{a+c+d}=\frac{a+b+c+d}{a+b+d}=\frac{a+b+c+d}{a+c+b}\)
=> b+c+d = a+c+d = a+b+d = a+c+b
=> a=b=c=d
=> GTBT = 1+1+1+1 =4