Answer :
[tex] \left \{ {{-10x-8y=-20\ \ \ |\cdot2} \atop {20x+16y=4}} \right. \\\\ \left \{ {{-20x-16y=-40} \atop {20x+16y=4}} \right. \\+-------\\\\0\neq-36\\\\There\ are\ no\ solution.[/tex]
solving for y:
20x + 16y = 4 20(1/5 - 4/5y) + 16y = 4
- 16y -16y 4 - 16y +16y = 4
20x = 4- 16y (-16y + 16y cancel out)
20 4=4
x = 2/10- 4/5y infinite solution
10x - 8y = 20 10(2/1 +4/5y) - 8y =20
+8y +8y 20 + 8y - 8y = 20
10x = 20 + 8y (8y - 8y cancels out)
10 20 = 20
x = 2/1 + 4/5y infinite solution
20x + 16y = 4 20(1/5 - 4/5y) + 16y = 4
- 16y -16y 4 - 16y +16y = 4
20x = 4- 16y (-16y + 16y cancel out)
20 4=4
x = 2/10- 4/5y infinite solution
10x - 8y = 20 10(2/1 +4/5y) - 8y =20
+8y +8y 20 + 8y - 8y = 20
10x = 20 + 8y (8y - 8y cancels out)
10 20 = 20
x = 2/1 + 4/5y infinite solution