Question 7
Given positive real numbers $a, b, c, d$ that satisfy equalities
$$
a^2 + d^2 - ad = b^2 + c^2 + bc \quad \text{and} \quad a^2 + b^2 = c^2 + d^2,
$$
find all possible values of the expression $\frac{ab+cd}{ad+bc}$.
$$
a^2 + d^2 - ad = b^2 + c^2 + bc \quad \text{and} \quad a^2 + b^2 = c^2 + d^2,
$$
find all possible values of the expression $\frac{ab+cd}{ad+bc}$.