# How does this textbook go from this step to the next? I'm very confused.

Here's a picture detailing the question:

In the second half of the picture where it says

$$1 = 4 - 1 \cdot (11 - 2 \cdot 4)\\ 1 = 3 \cdot 4 - 1 \cdot 11$$

How did they jump from that first equation to the next? Where'd the $3$ come from?

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You have $$4-1\cdot(11-2\cdot 4)=4-1\cdot 11+2\cdot 4=3\cdot 4-1\cdot 11$$ by distributing the $-1$ in front of $(11-2\cdot 4)$ and collecting multiples of $4$.