My Favorite Song

Mariner's Revenge By: The Decemberists

Lyrics:
We are two mariners
Our ship's sole survivors
In this belly of a whale
It's ribs our ceiling beams
It's guts our carpeting
I guess we have some time to kill
You may not remember me
I was a child of three
And you, a lad of eighteen
But, I remember you
And I will relate to you
How our histories interweave
At the time you were
A rake and a roustabout
Spending all your money
On the whores and hounds
Oh oh
You had a charming air
All cheap and debonair
My widowed mother found so sweet
And so she took you in
Her sheets still warm with him
Now filled with filth and foul disease
As time wore on you proved
A debt-ridden drunken mess
Leaving my mother
A poor consumptive wretch
Oh oh
And then you disappeared
Your gambling arrears
The only thing you left behind
And then the magistrate
Reclaimed our small estate
And my poor mother lost her mind
Then, one day in spring
My dear sweet mother died
But, before she did
I took her hand as she, dying, cried
Oh oh
Find him, bind him
Tie him to a pole and break
His fingers to splinters
Drag him to a hole until he
Wakes up naked
Clawing at the ceiling
Of his grave
It took me fifteen years
To swallow all my tears
Among the urchins in the street
Until a priory
Took pity and hired me
To keep their vestry nice and neat
But, never once in the employ
Of these holy men
Did I ever, once turn my mind
From the thought of revenge
Oh oh
One night I overheard
The prior exchanging words
With a penitent whaler from the sea
The captain of his ship
Who matched you toe to tip
Was known for wanton cruelty
The following day, I shipped to sea
With a privateer
And in the whistle of the wind
I could almost hear
Oh oh
Find him, bind him
Tie him to a pole and break
His fingers to splinters
Drag him to a hole until he
Wakes up naked
Clawing at the ceiling
Of his grave
There is one thing I must say to you
As you sail across the sea
Always, your mother will watch over you
As you avenge this wicked deed
And then, that fateful night
We had you in our sight
After twenty months at sea
Your starboard flank abeam
I was getting my muskets clean
When came this rumbling from beneath
The ocean shook
The sky went black and the captain quailed
And before us grew
The angry jaws of a giant whale
Oh oh
Oh
Don't know how I survived
The crew all was chewed alive
I must have slipped between his teeth
But, oh! What providence
What divine intelligence
That you should survive as well as me
It gives my heart great joy
To see your eyes fill with fear
To lean in close and I will whisper
The last words you'll hear
Oh oh

I wish I was fond of math like I am fond of this song. The song is nice to listen to, and it tells a story, but what does this mean:ax+by=c