Twenty people pre-bought plane tickets at a price of $155 per ticket. Thirty people bought their plane tickets at the gate and they each paid $200 for their ticket. How many more dollars did the people at the gate pay for their tickets than those passengers that pre-bought their tickets?
Pre-bought: 20 people * $155 = $
<gadget id="calculator">20*155</gadget>
<output>3_100</output>
3100.
Gate bought: 30 people * $200 = $
<gadget id="calculator">30*200</gadget>
<output>6_000</output>
6000
$6000 - $3100 = $
<gadget id="calculator">6000-3100</gadget>
<output>2_900</output>
2900.
The passengers that paid at the gate paid $2900 more dollars than those who pre-bought their tickets.

<result>2_900</result>