Question 511333
x = one number
y = another number
.
x  + 9 = y
or
x = y -9
.
x + y = 27
.
substitute
.
(y-9) + y = 27
2y = 36
y = 18
.
x = 9
.
x+y = 27
.
Answer: x = 9, y = 18
.
Done.