James hires a horse-drawn carriage from 5 PM to 9 PM.  He gets 1 hour free.  The first paid hour is $15 and each hour after that is twice the cost.  How much did he pay?
He got it for 9-5=
<gadget id="calculator">9-5</gadget>
<output>4</output>
4 hours.
He pays for 4-1=
<gadget id="calculator">4-1</gadget>
<output>3</output>
3 hours.
The first hour cost 1*15=$
<gadget id="calculator">1*15</gadget>
<output>15</output>
15.
The other 3-1=2 hours are more expensive.
They cost 15*2=$
<gadget id="calculator">15*2</gadget>
<output>30</output>
30 per hour.
So those 2 hours cost 2*30=$
<gadget id="calculator">2*30</gadget>
<output>60</output>
60.
So he pays 60+15=$
<gadget id="calculator">60+15</gadget>
<output>75</output>
75 per hours.

<result>75</result>