Help please I don't understand

We have 2 numbers $x,y$

$x=4y$ (1)

$x+y=155$<=> We are replacing the (1) => $4y+y=155$ <=> $5y=155$ <=> $y=31$

so we are replacing in the (1) $x=4\times31$<=> $x=124$

so the two numbers? is $31$ and $124$

Hope this helps!

number 1 = x, number 2 = 155-x.

We have the equation $x = 4(155-x)$, which simplifies into $x = 620 - 4x$. Isolating x, we have $5x=620$, which simplifies into $x = 124$. The second number is $155-124$, which is $31$. Done, you are welcome. 

sorry im confused

Let the smaller number   = N

The greater number  = 4 times N   = 4N

And we know that 

N + 4N   = 155

5N    = 155      divide both sides by 5

N =  31     [ the smaller number ]

And the larger number is  4 ( 31)  =  124