A rental car company charges $100 flat fee and $.25 per mile. Write an equation to find the cost "c" for "m" miles

So you would look at the formula as you would slope intercept:

y = mx + b

m = slope

b = y intercept

Each mile costs $.25 so that would be the slope

The entry fee would be the y intercept

X in this equation are the miles

If m = miles

And c = cost than ...

The equation is c =.25 (m) + 100