Question

Решите систему уравнений: 20 = 5 х + y (40-5x)/ 5 =(20-3y)/1 х= ? ,у =?

Answer 1

$\left \{ {{20=5x+y} \atop { \frac{40-5x}{5}=20-3y}} \right.$
$\left \{ {{y=20-5x} \atop { \frac{40-5x}{5} =20-3(20-5x)}} \right.$
$\left \{ {{y=20-5x} \atop {40-5x=100-15(20-5x)}} \right.$
$\left \{ {{y=20-5x} \atop {40-5x=100-300+75x}} \right.$
$\left \{ {{y=20-5x} \atop {40-5x=-200+75x}} \right.$
$\left \{ {{y=20-5x} \atop {-80x=-240}} \right.$
$\left \{ {{y=20-5x} \atop {x=3}} \right.$
$\left \{ {{y=20-5*3} \atop {x=3}} \right.$
$\left \{ {{y=5} \atop {x=3}} \right.$