Question

Solve:
3x-12y=30
5y+10x=100

Answer 1

$3x-12y=30\\3x=12y+30\\\frac{3x}{3}=\frac{12y+30}{3}\\x=4y+10\\\\5y+10(4y+10)=100\\5y+40y+100=100\\45y+100=100\\\frac{45y}{45}=\frac{100-100}{45}\\y=0\\3x-12(0)=30\\3x=30\\x=10\\x=10,y=0$

Answer 2

3x-12y=30
*divide by 3*
x-4y=10

5y+10x=100
*divide by 5*
y+2x=20
x=4y+10
y+2(4y+10)=20
y+8y+20=20
9y=0
y=0
10x=100
x=10
(10,0)