sum 18 diffrence is 4

Answer 1

To start, we can set up two equations.

x + y = 18 and x - y = 4

We now need to solve for one of these variables in terms of the other. I am choosing to solve for x, but either way will work. I'm using the second equation and solving for x by adding y to each side, which gives me

x = 4 + y

Now that I have a value for x, I can plug this into my first equation

4 + y + y = 18

Combining like terms gives me

4 + 2y = 18

Subtracting 4 from both sides leaves

2y = 14

And dividing by 2 to solve for y gets

y = 7

We now know one number, and to solve for the other we can plug our y value into either equation

x + 7 = 18

Subtracting seven from both sides yields the x value

x = 11

So the two numbers are 11 and 7