Step-by-step explanation:
you made a lot of typos in the text.
I assume your meant the following :
the sum of two numbers is eight.
one number is four less than the other number.
the numbers : x, y
x + y = 8
x = y - 4
we use the second equation in the first :
y - 4 + y = 8
2y - 4 = 8
2y = 12
y = 6
x = y - 4 = 6 - 4 = 2