Question 2If $a,b,c,d$ are real numbers such that $$\frac{b+c+d}{a}=\frac{a+c+d}{b}=\frac{a+b+d}{c}=\frac{a+b+c}{d}=r,$$ find the value of $r$.$3$$1$$-1$$3$ or $1$$3$ or $-1$