The y-intercept is where on the graph the line is intersecting the y=axis. Slope is in the form y=mx+b (b=y-intercept, mx=how far up and over.)
Real world example could be:
Consider x is time in minutes
Consider y is the amount of fish food required in grams
The equation could then represent how much food (in grams) that a fish needs to be fed x minutes after it was previously fed.
To solve this, we simply need to remember our rules about order of operations. They tell us that first, we should distribute the 2 with the rest of the parentheses.
5-2(x-3)
5-2x+6
Next, we should combine our like-terms.
5-2x+6
11-2x
Seeing as we do not know the value of the variable, the simplest form of the expression is 11-2x.
255/56 = 4.55....
You can't have 0.55... buses so you round that up to 1.
Therefore 4+1 = 5 so 5 buses would be the minimum.