X plus y equals 9 x-y equals 3?

Answer 1

12

Answer 2

X + Y = 9 and X - Y = 3

Since 9 is three times 3, then

X + Y = 3 (X - Y)

which means that

X + Y = 3X - 3Y

so if we subtract X from both sides, we get

Y = 2X - 3Y

and if we then add 3Y to both sides, we get

4Y = 2X

then divide both sides by 2, giving us

2Y = X

Now, if we replace X with 2Y in the original equations, that gives us

2Y + Y = 9 and 2Y - Y = 3

Or,

3Y = 9 and Y = 3

Now we know that Y = 3 and 2Y = X, so I'll leave the last step (figuring out X) for you to do.