Question

State the equation for: The sum of two numbers is 21. One number is one more than the other.

Answer 1

So,

Let "x" and "y" be the numbers that we're asking for.

As we know, one number is one more than the other, so we could write:

$x+y=21$

And,

$y=x+1$

Now, the equation that we could state is:

$x+x+1=21$