Hi Brainiac
x+y=3
3x+3y=15
We need to solve for x+y=3 for x
So let's start by adding -y to both sides
x+y-y=3-y
x= -y+3
Now we need to substitute -y+3 for x in 3x+3y=15
3x+3y=15
3(-y+3)+3=15
9=15
Next, add -9
9-9 = 15-9
0=6
Answer: No Solutions
I hope that's help:0