$7.78 \quad\left\{\begin{array}{l}y-\log _{3} x=1 \\ x^{y}=3^{12}\end{array}\right.$

$7.79\left\{\begin{array}{l}\log _{x}(3 x+2 y)=2, \\ \log _{y}(2 x+3 y)=2 .\end{array}\right.$
7.78 Instruction. Take the logarithm of the second equation to the base 3.

Answer: $(27 ; 4),\left(\frac{1}{81} ;-3\right)$.