One number is one less than five times another ....
Let one number be x
The other number is 5x - 1
Their sum ...
x + 5x - 1 = 6x - 1
Their sum is decreased by 3
6x - 1 - 3 = 6x - 4
The result is eight
6x - 4 = 8
6x = 8 + 4
6x = 12
x = 2
x = 2
5x - 1 = 5(2) - 1 = 9
One number is 2 and the other is 9.