Most online ads typically charge by the click. An advertiser's total fee, \(d\), in dollars, is given by the equation \( d=\dfrac{c+20}{4}\), where \(c\) is
the number of times the advertisement has been clicked. By how much does the total fee increase for each click of the advertisement?
If we break apart the fraction, we can seperate the equation into the rate and constant portions.
$$ d=\frac{c+20}{4} $$
$$ d=\frac{c}{4}+5$$
The slope, or rate, given by click per dollar, is \(\dfrac{1}{4}\). This translates to \(\boxed{\$0.25}\) per click.
We can choose an arbitrary situation. For example, compare the price of 1 click versus 2 clicks.
1 click
$$ d=\frac{c+20}{4} $$
$$ d=\frac{1+20}{4} $$
$$ d= \frac{21}{4}$$
2 clicks
$$ d=\frac{c+20}{4} $$
$$ d=\frac{2+20}{4} $$
$$ d= \frac{22}{4}$$
Finding the difference:
$$ \frac{22}{4} -\frac{21}{4}$$
$$ = \frac{1}{4} $$
$$ =\boxed{\$0.25} $$