Помогите пожалуйста с двумя системами

264.1)
$\left \{ {{5^x+5^y=30} \atop {5^x-5^y=20}} \right.$
$\left \{ {{5^x=30-5^y} \atop {5^x-5^y=20}} \right.$
$\left \{ {{5^x=30-5^y} \atop {30-5^y-5^y=20}} \right.$
$\left \{ {{5^x=30-5^y} \atop {30-2*5^y=20}} \right.$
$\left \{ {{5^x=30-5^y} \atop {-2*5^y=-10}} \right.$
$\left \{ {{5^x=30-5^y} \atop {5^y=5}} \right.$
$\left \{ {{5^x=30-5^y} \atop {y=1}} \right.$
$\left \{ {{5^x=30-5=25} \atop {y=1}} \right.$
$\left \{ {{x=2} \atop {y=1}} \right.$

265.1)
$\left \{ {{3*2^x+2*3^y=12} \atop {2^x-3^y=-1}} \right.$
$\left \{ {{3*2^x+2*3^y=12} \atop {2^x=3^y-1}} \right.$
$\left \{ {{3*(3^y-1)+2*3^y=12} \atop {2^x=3^y-1}} \right.$
$\left \{ {{3*3^y-3+2*3^y=12} \atop {2^x=3^y-1}} \right.$
$\left \{ {{5*3^y=15} \atop {2^x=3^y-1}} \right.$
$\left \{ {{3^y=3} \atop {2^x=3^y-1}} \right.$
$\left \{ {{y=1} \atop {2^x=3^y-1}} \right.$
$\left \{ {{y=1} \atop {2^x=3^1-1=2}} \right.$
$\left \{ {{y=1} \atop {x=1}} \right.$