Hi there!
We will create a system of equations to find the numbers you are looking for.
Let's say that the x is one number, and the y is the other number, system looks like this:
x + y = 51
x - y = 9
_________ since the y has different sign in both equations, we will add these two equations together and solve it by x, like this:
2x = 60
x = 60/2
x = 30 => x + y = 51
y = 51 - x
y = 51 - 30
y = 21
The value of the smaller number is 21.
Hope this helps!
